disapproval If you describe something as a rehash, you are criticizing it because it repeats old ideas, facts, or themes, though some things have been changed to make it appear new. The Observer found the play `a feeble rehash of familiar Miller themes'
disapproval If you say that someone rehashes old ideas, facts, or accusations, you disapprove of the fact that they present them in a slightly different way so that they seem new or original. They've taken some of the best bits out of the best things and rehashed them
old material that is slightly reworked and used again; "merely a dull rehash of his first novel"
To rework old material (physical material, ideas, documents etc), redo some work, with some variations