Showing Invisible window without resetting data

I have application which has lots of windows and for navigation purpose when i goto next window on a button click on current window the current window is hidden simply and next window is instantiated.  But when i try to go back using an instance of previous window all data inside is getting reset, is it a way to make previous window visible without creating instance .

window 1:

go_next_window

{ Window2 win2 = new Window2();

win2.show();

this.visibilty = visibility.hidden;

}

Window2:

go_back_window1

{ this.visibility = visibility.hidden

Window1 win1 = new Window1();  //reset all data in list  is there way to show it without creating instance

win1.show();

}