Before this thread gets dug any deeper - I think we should probably clarify the difference between YOUR meaning of the word "upgrade" and the Disney Cast Member's meaning of the word "upgrade". Because chances are, they are not the same.
When you say "I'd like to upgrade", chances are you mean that you'd like to add more days.
If this were a test, you'd only get partial credit.
When a Disney Cast Member hears the word "upgrade", they take your definition, and have to add to it: "add more days....AND get FULL credit for the cost of the ticket"
SO - when you're asking a cast member to upgrade, you're asking for full retail price back on a ticket. That can be done in 2 instances, as we've hashed out here previously.
1.) The ticket is completely unused
2.) The ticket's first use was within the past 14 days
ONLY if your ticket falls into one of those 2 categories will you be able to upgrade the ticket.
Those two criteria will determine whether or not an upgrade is possible. Once you get past THAT hurdle, if you ARE eligible to upgrade, there's a few more ****y traps to get through.
Your ticket must be of equal or GREATER value with respect to USED entitlements, as well as length.
Entitlements is a fancy word for options. If you have the park hopper option, and have USED it, you will have to get the park hopper option on the new ticket. If you have the water park fun and more option, and have USED it, you will have to get the water park fun and more option on your new ticket. (This includes an upgrade to an annual pass - if you've used your water park fun and more option, you will have to purchase a premium annual pass). If you've got a 5 day ticket, your new ticket will have to have 5 or more days. I'm PRETTY sure this is the way things work. The last I heard, this was correct, but it may have been changed to having to get all the same options on the new ticket whether you've used them or not.
And the last ****y trap deals with annual passes. If you upgrade AFTER using the ticket, your anniversary date (fancy word for the date your pass will expire) will be on year from the day you first used the ticket you upgraded. So if you use a ticket on January 14, 2007, and upgrade it on January 20, 2007 - your anniversary date would be January 14,2008 - meaning you'd lose 6 days.
So what happens if your ticket doesn't fall into one of those two categories? Then you can try for credit from a partially used pass. There's one rule to remember with this:
DISNEY DOESN'T LIKE DOING IT.
There are two sepcifics I'm sure of. You CAN'T get any kind of credit from a partially used pass that was purchased BEFORE they began selling Magic Your Way tickets. So if you bought your tickets prior to January 5, 2005 - you're out of luck.
The other thing I'm sure of is that if you CAN get a dollar credit? Disney will gouge you. You won't get much credit for your unused days. They do this in an attempt to steer guests away from trying to get credit for these passes.
Up at the top of the Theme Park Attractions and Strategies board, in the stickies section, there's a thread entitled "EVERYTHING YOU ALWAYS WANTED TO KNOW ABOUT MAGIC YOUR WAY ADMISSION". There's a pretty exhaustive list of questions and answers in there. And don't be scared off by the fact that it's about a million pages long. The very first post is an FAQ.