If you have an additional line on your account - one without a contract using, say, an old flip phone - you should be able to upgrade by shifting that phone's upgrade to your existing line that's still in contract. This will re-initiate your contract to a full 2 years.
This is what I plan (hope) to do. But Vz changes the rules so often, I'm keeping my fingers crossed that I don't have to keep that flip-phone line afterwards - or that they will even let me upgrade using the flip-phone's eligibility. I'm almost afraid to ask... but will when the iPh 5 is available.