Naturally you don't want to lose any data from your live site.

That's why the BEST next step is to actually upgrade your live site directly, now that you've got all the kinks of your upgrade sorted out:

a) now, set your live store to down-for-maintenance
b) RE-DO the entire upgrade on your live site (which will be very easy, since you've already done it all once, sorted out any conflicts, and have made good notes about any settings changes so you can do them all in a couple minutes again on the new site):
- i) upload the new files to the old site
- ii) delete obsolete files from the old site
- iii) upload the zc_install folder for the new version to the old site
- iv) run zc_install to update the live site database
- v) delete the zc_install folder
- vi) do any admin configuration/settings updates as needed
c) take the live site back online again by turning off maintenance mode
d) delete your TEST site, since it's no longer needed (unless you want to keep it for additional testing activity)

You WILL NOT use your TEST site as the LIVE site. It was for TESTING only.


Naturally, this whole process is easiest if you've already got a good clean reliable set of files on your new test site, and have made good notes about any special configuration changes or SQL Patches etc that were required when you were testing and readying the test site to be sure it works as desired.
Doing it this way means your live store will only be in maintenance mode for a brief period of time.