When's your exam? Sounds like you have to take it really soon,
... Also, does the exam require you to know how to write the kanji or just recognize them?
Maybe it would help if you figure out exactly how long it takes for you to learn each kanji on average... Personally I take about 3 minutes per kanji. So, if you can do some rough calculation like that, you can figure out how much time to spend. (Learning kanji is a pretty linear process, just got to put in the time.)
As for learning techniques, I think everyone's different, but here's my thoughts:
-Studying kanji is like feeding a baby... you scoop some food into its mouth, it spits half of it out, so you keep scooping and scooping until it stays in! In other words, you can't just memorize a kanji on Monday and expect it to stay in your brain until Friday. So, it helps to review stuff you already learned.
-Here's my own "kanji study approach" in case it might help, not necessarily the best, and I haven't tried it for cramming hundreds of kanji per week like you probably are going to do, but oh well
* Every week, take a new batch of 35 kanji from the "Kanji Pict-o-Grafix" book.
* Every day, I go through the entire batch, focusing on a particular aspect of kanji:
-Monday: Learn meanings, also write each Kanji only ONCE- not so much to learn how to write the kanji perfectly at this point, but just so I am aware which radicals are used in each kanji, etc.
-Tuesday: same as Monday
-Wednesday: Write each kanji multiple times, paying attention to stroke order and proportions
-Thursday: Learn most common on/kun readings. If I have trouble learning one, I make up a story for it. For example, the kanji for "gather" (ツ集), the on reading is "shuu", so my "story" was "gather your shuus" (shoes).
-Friday: same as Thursday
-Saturday: same as Thursday
-Sunday: review all aspects of Kanji
* I try to also spend a little time each week reviewing kanji from previous weeks.. I'm pretty good about remembering meanings, but I often find I forget the readings so reviewing is helpful.
Good luck,
Raj