If you're on android, you can download the newer .apk and execute it on your phone to update your game files.
On other systems, you can either use the update files or download the full game again.
- If you have the previous update, you can copy and paste the update files into the game folder to overwrite the existing files with the newer versions of them. Don't use the update files if you skipped one or more updates, as the .zip only contains what has been changed since the last update!
- If you're more than one update behind, download the full game again, and copy&paste the content of the www/save folder from the old game version to the same location in the new game version.
I made a video about both options here: