I'm using GoDaddy. 
1. Under cPanel there is section called Files. 
2. Click File Manager.  There you should see your Linux file system. 
3. Click on public_html.  AbanteCart leaves its upgrade files in this directory including upgrade.sql. 
4. Double clicking the file downloads it to your local machine. 
5. Go to your downloads directory on your local machine.  You can open it to see the sql commands that should have ran when the upgrade ran.  Look for a Create Table command that includes the table that AbanteCart says it is missing.  If its not there message back, otherwise keep going.

6.If your local machine is Windows don't save the file just close it out.  Windows saves with different carriage returns than UNIX based systems. 

7. Go back to cPanel and look in the section called Databases. 
8. Click phpMyAdmin. 
9. On the left side is a list of your schemas.  If you let AbanteCart build the database the name will look like a string of numbers and letters.  Click that. 
10. If you break the tree down you should see a whole bunch of tables that start with ac_ .  Now at the top of the screen click Import. 
11. Click Choose File. 
12. Select upgrade.sql that you downloaded. 
13. Leave the other options default then click Go.  You should be good to go after that.

Notes:  For this update I didn't see anything that would effect any of the other tables so I didn't change the prefix.  Not the safest way, but in this instance I didn't have anything in the tables that were being altered.

If you have data that you need in the tables that the upgrade.sql file will alter then LISTEN to Basara and follow the AbanteCart directions.