There's a currently an option to
buy out your contract and start a new one with a new phone. Offer is only good in Sprint corporate stores. Offer expires after 4/15.
Your other option would be to wait for Sprint to change the terms and conditions of the contract:
"If a change we make to the Agreement is material and has a material adverse effect on Services under your Term Commitment, you may terminate each line of Service materially affected without incurring an Early Termination Fee only if you: (a) call us within 30 days after the effective date of the change; and (b) specifically advise us that you wish to cancel Services because of a material change to the Agreement that we have made. If you do not cancel Service within 30 days of the change, an Early Termination Fee will apply if you terminate Services before the end of any applicable Term Commitment."
You can't count on when Sprint will make a change, but Sprint has been a lot more energetic about making changes in the last year or so. In either case you can start a new contract immediately after either buying out or citing a material change in the contract's terms and conditions.