Repeat exposure is usually how it starts to stick. I worked as an instructor for a while, and I certainly didn't know everything by heart from the beginning. However after teaching the same thing to a lot of people you will eventually be able to quote regulations by number and word by word, haha.
A word of advice would be to try and find some students to give free tutoring (if you are working on your CFI, not really sure if you are one, or studying for one by your post). When you have to put everything into words that a student will understand, your understanding will get a boost as well, and it will be easier to remember. At least it was for me