Other forms: renegotiated; renegotiating; renegotiates
To renegotiate is to go back to a previously settled agreement and discuss the details all over again. If you have to renegotiate the terms of your dog walking job, it may feel like you're starting from scratch.
To negotiate is to bargain, confer, or compromise until you reach a deal with another person or group. When you renegotiate, you do it again. After you move into a new apartment and realize there's a loud music store downstairs, you might try to renegotiate your lease, asking your landlord to reduce your rent. And countries frequently renegotiate treaties, returning to haggle over details, making sure they benefit from the agreement.