On android if you download the apk and install it as an update you should keep your saves.
NEVER UNINSTALL, you will lose your saves.
You can make a backup, just get a file manager that can access the folder (Solid Explorer is recommended) and go to:
Android/data/com.domain.corruptedkingdoms/files/saves
Grab the files and copy them somewhere else, you can even move them to your computer.