Rereading is the art of re-reading. Yes, you read that right. Re-reading. It's like re-watching a movie, but with more pages.
Step 1: Read the first paragraph. Not the entire book. Just the first paragraph. Repeat as necessary.
Example: If the book is 200 pages long, read the first paragraph 200 times. That's 200 pages of re-reading right there!
Subpage: Step 2: Re-read the first chapter. Re-read the second chapter.
Subpage: Step 3: Re-read the entire book. But only in your head.