Here are some things that helped me, personally:
Proofs usually have two things that you can focus on if you're having trouble getting them internalised: intro formalism and some key twists.
The intro formalism is just the stuff that will be used in the proof - you've seen this: new definitions, maybe new symbols, and maybe some assumptions and 'wordy stuff'. Focus on understanding and recalling these first. Even if you can find it easier to recall other, more mathematical facts about the proof, it's possible you'll end up with a muddled argument, because the intro stuff usually makes things precise, and eliminates edge cases.
Once you've got the beginning formalism sorted out in your mind, the rest is the hard stuff: the key twists, the actual logic being performed. What I found useful is to avoid memorising every logical step in a derivation as a separate thing. Instead, memorise a few in-between steps and construct exercises for yourself by trying to go from the intro stuff and the in-between steps to the actual final proof.
I used to have a little notebook with my own exercises in them, all constructed from proofs that I had to memorise. I didn't do this for each and every proof, just for the ones that were conceptually troublesome.
The key is to make the memorisation of proofs more like regular mathematics with exercises - with the full proofs being the solution to the exercises.
Another point - and this is somewhat unorthodox: for very hard proofs, the key mathematical machinery being used can be set at a level that's actually too high for your current course. I found this quite frustrating, so (in these cases only) I decided to focus on (almost) rote memorisation first, and then understanding. I know that goes against the usual advice of understanding always trumping mere recall, but exams that force you to memorise lots of proofs are an artificial condition anyway; real-world maths isn't like this. So weigh this for yourself - maybe start with memorising hard stuff, then gradually chip away at it and try to understand it if you can.
All this obviously takes time, and for ~50 proofs this implies a substantial amount of work. I'm guessing you still have a fair amount of time left until your exam, so it's best to do this stuff early and consistently.
I've got a chapter on memorisation in my book about maths-heavy exams [1] - but it's not a free ebook. However, if you want it, send me an email and I'll send you the .mobi if you wish (or we can share via dropbox, rapidshare - we're spoilt for choice :)) - maybe some parts of it could help.
[1]: www.amazon.com/Exam-Mastery-excel-maths-heavy-ebook/dp/B00AMU20HE/ref=sr_1_4?ie=UTF8&qid=1355929591&sr=8-4&keywords=exam+mastery