What is it called when you renew a contract?

Renewing a contract goes by several names depending on the mechanism: a renewal (a new term on the same or updated terms), an extension (lengthening the current term without creating a new one, a subtle legal difference), auto-renewal or evergreen renewal (automatic continuation unless notice is given), reinstatement (reviving an already-expired agreement), and novation (technically a replacement contract, sometimes with a new party stepping in).

The distinction that matters most in practice is renewal vs. extension: a renewal often resets terms and re-opens negotiation, while an extension typically carries everything forward unchanged. Which one your contract does is written in its renewal clause, which is worth reading before the date arrives, because the clause also hides the notice window that decides whether you have a say at all.