How do you clear something like eventdata.Key so that I can run the function again?

I'm making a program that requires the user to type a word, hit enter and then compare the word to the one on the screen but I need to know how to clear the eventdata.Key so that the user can use the code I have written again when the next word pops up.

Here is what I have so far:

%create explanation message
uicontrol('style', 'text', 'units', 'normalized', 'position', [ .33 .1 .33 .05], 'string', 'Enter your responce below:');

%Position score counter
score_h = uicontrol('style', 'text', 'units', 'normalized', 'position', [.1 0 .1 .1], 'string', '0');

%Score text
uicontrol('style', 'text', 'units', 'normalized', 'position', [.1 .1 .1 .05], 'string', 'Score:');

%Create message area and word display area
word_h = uicontrol('style', 'text', 'units', 'normalized', 'position', [.35 .5 .3 .2],...
    'string', 'Welcome to Speed Typer! Type the words as quickly as you can as they pop up and hit enter! Type ''start'' and hit enter to begin.');

%Create level display and label
uicontrol('style', 'text', 'units', 'normalized', 'position', [.8 .1 .1 .05], 'string', 'Level:')
level_h = uicontrol('style', 'text', 'units', 'normalized', 'position', [.8 0 .1 .1], 'string', 'N/A');

%Create typing area to start game then remove when done being used
textbox_hstart = uicontrol('style', 'edit', 'units', 'normalized', 'position', ...
    [.33 .04 .33 .04], 'keypressfcn', {@keypress, word_h, level_h, score_h,...
    beginner,easy, medium, hard, expert});

Here is the function it keeps skipping through the words because it's reading the eventdata.Key as always being tru:

function keypress(hObject, eventdata, word_h, level_h, score_h, beginner, easy, medium, hard, expert)

%Determine if the return key ws pressed, and check if they enters 'start'
counter = 0;
word = 'start';
game_on = 0;
if strcmp(eventdata.Key, 'return') == 1
    import java.awt.Robot;
    import java.awt.event.KeyEvent;
    robot=Robot;
    robot.keyPress(KeyEvent.VK_ENTER);
    pause(0.01)
    robot.keyRelease(KeyEvent.VK_ENTER);
    if strcmp(get(hObject, 'string'), 'start') == 1
        word = beginner{randi([1,20])};
        set(word_h, 'string', word);
        set(level_h, 'string', 'Beginner')
        %Start timer
        gamestart = 1;
    end

      if gamestart == 1
          for k = 1:50
              if strcmp(eventdata.Key, 'return') == 1
                  import java.awt.Robot;
                  import java.awt.event.KeyEvent;
                  robot=Robot;
                  robot.keyPress(KeyEvent.VK_ENTER);
                  pause(0.01)
                  robot.keyRelease(KeyEvent.VK_ENTER);
                  if strcmp(get(hObject, 'string'), word) == 1
                      set(score_h, 'string', num2str(str2double(get(score_h, 'string'))+1));
                      counter = counter+1;
                      if counter <= 10
                          set(level_h, 'string', 'Beginner');
                          word = beginner{randi([1,20])};
                          set(word_h, 'string', word);
                          k = k+1;
                      elseif counter > 10 || counter <= 20
                          set(level_h, 'string', 'Easy');
                          word = easy{randi([1,20])};
                          set(word_h, 'string', word);
                          k = k+1;
                      elseif counter > 20 || counter <= 30
                          set(level_h, 'string', 'Medium');
                          word = medium{randi([1,20])};
                          set(word_h, 'string', word);
                          k = k+1;
                      elseif counter > 30 || counter <= 40
                          set(level_h, 'string', 'Hard');
                          word = hard{randi([1,20])};
                          set(word_h, 'string', word);
                          k = k+1;
                      elseif counter > 40
                          set(level_h, 'string', 'Expert');
                          word = expert{randi([1,20])};
                          set(word_h, 'string', word);
                          k = k+1;
                      end
                  elseif strcmp(get(hObject, 'string'), word) == 0
                      set(level_h, 'string', 'N/A');
                      %Stop timer
                      %calculate score
                      k = 50;
                      gamestart = 0;
                  end
              end
          end
      end

      %determine if key pressed was enter
      %compare string in text box to 'start'

      %If string matches:
      %change word on screen
      %change level

      %determine if enter was pressed
      %compare string on screen to users string

      %if string is the same:
      %add to score
      %check if level needs to be updated (add to counter if not)
      %display new word
      %repeat

      %if string is different:
      %change level back to N/A
      %stop timer
      %calculate and display score
  end