I think it is OK to repost if it did not receive much support and you would like to try a different tag. Also it is acceptable to add changes and post, but I think if you are not going to make changes, you should at least let people know that you are reposting an old post. If people wish to vote for it and have not seen it before and may be beneficial then share I say. But when people post the same thing multiple times in a row in a short period of time, it should be frowned upon