How many years is a signed Configuration Management Plan (CMP) good for, before it needs to be re-signed by the approving authority?
The Configuration Management Plan (CMP) is a living document. That means that the Plan itself specifies who may make changes of what type, as well as how often the Plan must be reviewed and who approves it.
Your organization may already have a standard approach for developing a CMP. It should align with the guidance in MIL-HDBK-61B Configuration Management Guidance. https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=202239