I've taken it four times (Civil PE Exam). My advice is to change things up. I even changed my job to reflect the new sub-discipline I was going to take (WRE). The last and final time I took it, I gave myself a year to unwind and untangle the cycle of repeat studying that did not work. There is a point of diminishing returns where if you keep studying it won't help out. I would read the CERM one day and do problems another day.
I would make a table of contents that would span multiple references, so I can find a certain problem or type of problem anywhere. Look at my water treatment TOC for reference. I would try to reference a problem and make sure I can solve every missing variable in it without the other. Everything in parenthesis in my TOC would be the provided variables and the text in front would be the variable I'm looking for. The way I built the TOC, if I don't recall a question that i've study. I can still find it. What you wanna do is tap into your memory. You don't need to know everything step by step in memory as long as you wrote out the steps properly you should be fine. Good Luck!