PlotWindow problem

[Gerhard-5]

Hello,
I have plotted some values in a PlotWindow.

Now I want to do some more plottings on this Plotwindow in the following way.

add new values to the values on the old PlotWindow
show them
clear them

add new values ....
show them
clear them

 and so on ...

Is there a way to do this without always drawing the hole set of values?

Thanks for help