In a "for sale" ad the word "refit" means absolutely NOTHING!
As others have said, someone selling a boat might claim a "refit" for almost any little work that was done. You need to get a complete and specific list of the work that has been done, and when it was done.
Another example: a claim of "engine rebuilt recently" can mean almost anything. There are varying levels of engine
rebuilding and the word "recently" is completely subjective. My daughter is now 23-years-old, but there are times when it sure feels to me like she was in kindergarten pretty "recently."
So, again, completely ignore vague words like "refit," "recent," "redone," or anything like that. You want a specific, detailed list of what was done and exactly when it was done. If the buyer won't provide that then assume the worst!