Key Rotation

Changing the key, i.e., replacing it by a new key. The places that use the key or keys derived from it (e.g., authorized keys derived from an identity key, legitimate copies of the identity key, or certificates granted for a key) typically need to be correspondingly updated. With SSH user keys, it means replacing an identity key by a newly generated key and updating authorized keys correspondingly. 

See NISTIR 7966 for more information.