You're sort of doing things backwards. What you should have done was:

1. Upload the latest version of Zen Cart to the test site.
2. Create a new blank database for the test site.
3. Import your old database into it.
4. Reconfigure the two configure.php files for the test site address, database, MySQL User Name and Password.
5. Go to the test site address plus /zc_install and then select the "Upgrade Database Only"option.
6. You'd then have a test site using the latest Zen Cart with your database upgraded to the latest level. You could then test this all out, add your add-ons and test those before putting it all live.

However, as your live site has probably had new customers, new products added, and orders since you started this work, you will have to bite the bullet and upgrade the live database.

But you should only do this when you are certain that the test site is all working.

Then you put the live site "Down For Maintenance" while you copy all the test site folders and files to the live site (except for the two configure.php files), upload the zc_install folder for the test site version of Zen Cart to the live site, and run it selecting the "Upgrade Database Only" option.

Vger