How do I make just one plot stay in a figure, while other plots are removed/updated as I iterate through my loop

I'm trying to make the plot of a potential visible in my figure while I plot the time evolution of the wave function of a particle in the potential.

 V=diag(xvec.^2);  %V is potential and xvec is a vector

 figure(1)
 hold on
 plot(xvec,V);

And after this point I want "hold on" command to be turned off for the animation to make sense, but the plot of the potential V to still appear in my figure, while the loop below iterates through the time evolution.

 for t=0:dt:100*dt

     v=exp(-i*E(1:N)*t/hbar);
     Psi=v'*ev(:,1:N)'/sqrt(N);
     plot(xvec,abs(Psi).^2/dx)
     axis([-0.1*a 1.1*a 0 4])
     text(2.5*a,0.45,num2str(t))
     pause(.2)

 end

Answer 1

[Walter Roberson]

   V=diag(xvec.^2);  %V is potential and xvec is a vector

   fig = figure(1);
   ax = axes('Parent', fig);

   hold(ax, 'on')

   plot(ax, xvec, V);

   for t=0:dt:100*dt

       v = exp(-i*E(1:N)*t/hbar);
       Psi = v'*ev(:,1:N)'/sqrt(N);
       y = abs(Psi).^2/dx;

       if t == 0
          ph = plot(ax, xvec, y)
          axis(ax, [-0.1*a 1.1*a 0 4])
          th = text(ax, 2.5*a, 0.45, num2str(t));
       else
         set(ph, 'YData', y);
         set(th, 'String, num2str(t));
       end
       pause(.2)

   end
   hold(ax, 'off')

[John Klint]

Thanks mate, I got it to work with the delete command. :)