If you're on PC, just download and play, the saves should be there.
(RenPy games tend to create a backup saves folder in your computer's AppData folder, though I think this game doesn't, at least last I checked).
I don't play on mobile, but I suppose the same advice for both versions - download new version without deleting the old. Mobile you should probably move saves over before deleting the old, PC I think you can just delete it.