Backup app (Clash of Clans) data from the system partition; monitor app write activities
What ever you do to update your ROM, you are doing it wrong. Never ever should you wipe your /data partition during an update (it should automatically wipe /system). Inside the /data partition is all your data, so your Clash of Clans village as well.To backup and restore your village the Google+ option is working like a charm for me and all other people I know. Just remember to login with the same account you saved/linked it to and accept the warning about overwriting your level 1 village with your saved one.