phone at the full price. If you want the discounted price that comes w/ renewing your contract, you will have to change your plan.
For example, if you get an iphone 4S for the $199 2-year contract price, you will have to get a new plan on your phone. However, if you're ok forking out $649 for the no-contract price, then they'll let you keep your old plan. At least that's the way it was explained to me.