If it is on your phone, i am not able to help much, i don't play on there and there are many models that may have compatibility issues.
Renpy does autosaves every few dialogue boxes though, check your autosaves page when it crashes to load with almost no progress lost. I also suggest deleting old versions of the game, if you kept any, and consider transferring your saves to another device to make a backup via the cloud feature accessed via the settings, if you can. I think some also use Joiplay to play some renpy games, that could be an alternative, but i never tried it myself.
Otherwise, consider joining our Discord to get help from other people who might know more, it is on the game's page here and in preferences in the actual game.