how do i update the game without erasing previous files?
if youre in pc, just download it and go to load, if you have any of your old saves, just load one and you should be fine; if there is none, I usually jus take a save from the last version I had and paste it on the save file of the new one.
You have to save something befor so the saves file appears by itself.
For the saves just go to Uni(whichever is the version)/game/save
Then do the same to get to the one in the new file version.
For android, just make sure you have enough space for the new version and install it, it will update by itself.