You can try
hFigure = findall(0,'type','figure','name','Simulation')
That should give you the handle to all figures with the name Simulation. you can then do:
hLines = findall(hFigure,'type','line')
which should give you all the lines.
If you don't like decorating your figures with unique names, you can also use the 'tag' property on your lines, axes, whatever and search for that. Nothing user-visible, just something you can use to search against.