Thank you for the kind words and for playing our game!
The short answer is you don't have to change anything nor prepare for anything regarding your saves on the Windows version. Your saves will continue to exist because in the code it is the "same" game as far as the saves are concerned. Your saves are also stored elsewhere as a backup on the various systems to enable this (https://savelocation.net/renpy). Some saves me become broken/unusable as an unfortunate part of the development process but we do everything in our power to avoid that.
Now, I will say for Android in order for the best chance for the builds to work properly, you must uninstall the previous installation for the best chance of success and the build starting. This is also for the benefit of anyone else reading.