Did you try deleting the old game and installing the new update? That's strange.
I understand the trouble, I wish it was different, sadly it's not something that I can actually fix. It's an engine problem, all games using this engine (ren'py) cannot keep up save data between versions on Android. We tried to bring the issue to the boss making ren'py but he said it was not possible for some complicated technical reasons that I do not fully understand.