Hi i believe i know of a way though it requires a computer due to android being very high security on itself. Basically you would have to go to your "files" app, not "my files" as that one won't work, click on "android", "data", find the folder connected to lust doll. (I couldn't find it but maybe you have it, if not then you have to use a app to crack your current version to take the save files). Then you need to use a computer, plug into your phone, to then access your files install the new version and implant the save files into the new version. It's either that or just download the new version and have it update your current one but I don't know if that would keep your saves.