Why do my Prep Test scores keep getting worse?

Taking LSAT in January - really trying to break 170. I was pretty consistent in the upper 160s range, peaked at 169 for a couple tests, then decline decline decline. My most recent Prep Test was a 160 - worst I've gotten. I'm reviewing my wrong answers/reviewing content related to the types of questions I get wrong. I'm running Drills. I feel like I should be doing better but they keep getting worse. Any ideas?