Unfortunately your problem isn't the game it's the fact that Android updated their operating system, They have effectively sandboxed each and every app on the phone to make sure they cannot directly interact with each other The only way at this point of time to have the functionality you're speaking of is either have the game developer put into the game the ability to export the save which Ren'py can and does support, try updating instead of uninstalling, or and I really cannot advise this one root your phone.