Have you checked the rules?
viewtopic.php?f=41&t=46183
Please do not bump your thread before it falls off the front page.
That said, I do make a new post when I update the thread. Like selling something new. Which happens every two weeks, so not very often anyway.
Because the forum is so slow the thread never falls off the front page anymore...
I suppose you could say your case is similar.
You would not find a seller during the rest of the month, now you have a new chance and make sense to "reactivate" your thread.
I don't know what a mod would say about my theory tough xD