Depending on the platform. Will you keep your progress?
PC - Yes, if you haven't deleted the folder specified above, you can back it up just in case. But you don't have to keep the folder with the game.
Android - It's advised to back up the folder specified above before deleting the game, not to lose saves. However, if you're just installing a new version without deleting the old one, you should be fine.
Game saves are stored here:
PC - %AppData%\Roaming\RenPy\MurMur-#Numbers
Android 10 or older - Android\data\RenPy\MurMur-#Numbers
Android 11 or higher - Android\data\com.dd.murmur\files\saves