My manuscript was rejected by a publisher. Since that rejection, I have made several changes to the opening chapters that I feel would really improve my chances at getting accepted. Would it be considered bad, or is it somehow against the rules if I were to resubmit this retooled version of my manuscript? If I were to do this, would the editor even bother to look at it a second time, having rejected it before? Is this something that's even done? Thanks.