this may be a bit too late, but u could use it in the future. so instead of plainly trying to memorize, get a big paper and a pen, and write out ONLY the main points from each paragraph (you can look at your essay for reference for this 1st paper), and keep re-writing those stuff on new papers until you can write them all without having to look at the 1st paper. This literally helped me memorize an essay for my year 12 sac 1hr before the sac and it worked so good.
I do have to add that also trying to understand what you actually wrote in that essay could make it much easier than just reciting it over and over again, try to understand why you mentioned certain things in certain paragraphs and why it's structured the way it is.
hope this helps,