The re-write from what i understand, is editing each chapter.  I went through the entire manuscript trying to see where the punctuation may be off, the conversation may have strayed into something else, topics that really didn't make a hill of beans or make any sense.  I started my first novel in August 08, finished in January 09.  It has taken me from January to the beginning of this month, to edit.  Now, i am certain the literary agent may pick it clean even though i am satisfied with my work, but i would be willing to give it another round if she's wants it.  It is alot of work.  Anyway, that's what i've been told- RE-DO your masterpiece one chapter at a time.