Yeah, this is getting on my nerves. I've lost 3 posts already because I was over the limit. You can't go back and re-post, you have to re-write the entire message.
If you try to post and get the too fast message, you should be able to press the back button and have the stuff reappear saved in your browser how you typed it. I think this is part of forum code, so can we get this implemented? It would save a lot of hassle.
I know on my other board they have it if you post too fast you just press back and wait a few and press post.