What legal concept involves replacing an old contract with a new one?

The correct concept that involves replacing an old contract with a new one is novation. Novation occurs when both parties to a contract agree to replace an existing agreement with a new one, essentially discharging the original contract and creating a new legal obligation. This process requires the consent of all parties involved, and it is key to ensuring that the new contract fully replaces the old one, as opposed to merely modifying it.

In contrast, ratification refers to confirming or approving a previous act that may not have been authorized when performed. Abolition typically refers to the complete termination of something, such as a law or a practice, rather than a replacement with a new legal framework. Assignment, on the other hand, involves transferring rights or obligations under a contract to another party while the original contract remains in effect, rather than creating an entirely new contract. Thus, novation is uniquely suited to this situation as it specifically addresses the replacement of an old contract with a new one, marking a clear legal transition.