If you installed the APK version, it will usually ask you if you want to delete additional app data while uninstalling - which might include save files. So, if you uninstall, and you don't delete the extra app data, you should still have that data when you reinstall (but I don't know, for sure).
You could also use a file manager app to navigate to the game's directory and copy those files somewhere safe. Then, copy them back into that app's directory when you've reinstalled it. (I'd go ahead and do this anyway, just to have a backup in case the files are lost when you uninstall it.)
If you "installed" the web version, I don't know how you might go about that. :/