
Hmm, guess it depends on what you mean by upgrade.
Do you mean get a better room at the same resort you are already booked at for a lesser rate? I have never heard of anyone having any luck doing this ahead of time, but I guess you could always ask. You can try asking at check in if any better rooms are available, and how much it would be to upgrade, but it all depends on the resort and if anything is open. Though if you have a particular view in mind, it's better if you go ahead and book it to avoid disappointment.
Or do you mean call and try to get an upgraded resort (like going from value to deluxe)? Not that I know of, unless Disney overbooks or has a problem at the resort you are booked at and then they contact you to make an offer to get you to switch.
Or do you mean can you apply a deal that opens for the same time you are already booked for? Yes, you have to call (or have your TA call) and have them try to apply the code. They will modify your res and refund the difference if there is availability at your resort using that code. Otherwise you might have to consider changing resorts to be able to get the deal.
I have never seen a purely "upgrade" code for Disney...but who knows in the future?
There
have been reports of "upsells" though - apparently they are very rare, and happen when you are making your original reservation. They will appear on the CM's computer and they will then make the offer to you at that time.
Hopefully someone else will chime in with more info, maybe they've had a different experience.
HTH!
