How do I update the game without losing my saves?
Viewing post in WEEKLY RELEASE - v0.19.5! comments
Ren'Py stores saves in a "saves" subfolder in the "game" folder, which you can just manually transfer, but if you're running on Windows at least, it should also have a copy in your local storage that will follow the game.
If you use the itch launcher, it'll take care of updates for you and you won't have to worry about it.
Krellen covered it, but just so there's an "official" response:
All saves are automatically transferred when you boot up the latest version, so you don't have to worry about a thing. Just download, extract and play!
The only caveat is that if you're on Android DO NOT DELETE THE GAME! Or else all your saves will be gone forever.