hey!
so chances are you may be revising very passively such as reading your notes, writing out notes or highlighting. These are really good to get a overview for the topic or summarise information, however for it to go into your long term memory, its usually very ineffective for most people. You want to do revision techniques such as mindmaps where you connect dif ideas together, past paper questions and quizzes as they force you think and make you consider weather you really know the content or not. Flashcards are another great revision method as you can test yourself and if you cant answer the question, you know to go over that topic again through your notes, rather than read notes to topics you already may have a solid understanding of. teaching someone is another great way as it ensures you know the topic enough to tell someone else about it in the simplest of words. Hope this helps!