You mentioned that you'd backed up manually in the past...
If you open the ES File Explorer application and close any introductory messages, click on the Android folder (if you can't see it, click the HOME link found in the LOCAL menu on the left). Then Data. You're now looking for org.xbmc.kodi . You can now either copy that entire folder (longclick on the folder, select COPY at the bottom) to a USB device or SD card (click the PASTE button when in the right folder), then copy it back when you need to restore the backup. Or you can expand the TOOLS menu on the left, turn on Show hidden files option, normal (short) click on the org.xbmc.kodi folder, then the files folder. Now you can click the previously hidden .kodi folder, and copy and paste the USERDATA, MEDIA and ADDONS folders. I believe those are the only three you'll need (Media has the Wookie wallpaper/splashscreen in it).