Reinstall with same configuration

There is no config backup yet. What you can do is copy the config.xml file to the other system.
You will also need to keep the uuid of the single disk And assign it later to the raid. I know you can do this with ext4 filesystems.
Once there you will need to create the raid entries at config and fstab manually. Then proceed to mountOnce there in cli start running the omv-mkconf commands to pipe the config values to the current services.

At the end is a mess. I would just start again.

Also I forgot to mention the usernames, you can transfer the passwd and shadow file also to keep the passwords.

Agree w/ all of the above. I just reinstalled because um... Well, lets just say I wasn't really paying attention while upgrading, and accidentally upgraded to Jessie... I've tried backing up the config.xml, etc.. before but it ends up being just a big headache. I've come to the conclusion it's easier to just make notes on your settings, and just plug them all back in manually. If having a restorable backup is that important to you, then reinstall, and when things are perfectly how you want them, image the drive.