The phrase "complete rehash" means that something has been redone or reused entirely without any significant changes or improvements made to it. Full definition
My only contention is some issues are complete rehashes of earlier tiny home showcases. (tinyhousetalk.com)
I saw The Hangover Part II as a complete rehash of the original to the point that boredom / apathy sat in while I watched Bradley Cooper and Co. gallivant their way through Bangkok. (collider.com)