Nik, first, backup any data that's important to you.
Then go to Settings | About Phone | CyanogenMod Updates. See if the final release is available for you. If so, the update should proceed smoothly and all your data should be kept intact.
If not, download the final release, reboot in recovery, do not select to do a factory reset, then install the final release. The update should proceed smoothly and all your data should be kept intact.
As for myself, a few days ago I manually unlocked the bootloader, installed a custom recovery, and installed CM 10.2 RC1, doing a factory reset before installing because I was replacing the ROM that came with my phone. Then today, I updated to the final release with CyanogenMod Updates in Settings. I went from CM 10.2 RC1 to 10.2 Final with all my data intact. No factory reset was performed by CyanogenMod Updates.
Once you manually install CM with your custom recovery the first time, you should be able to update in the future from CyanogenMod Updates just like an OTA update.
Let me know how it goes!
HTC One (m7att)
— modified on Dec 4, 2013 8:59:08 PM