Plateauing?

I have been studying for the LSAT for about a year or so, on and off depending on whatever is going on in my life. I have taken the test and my highest score is a 164. I am trying to aim for a higher score so I can take a shot at a T-14 school (like Northwestern) with a GPA of 3.58. I took a practice test last week but it seems like I capped out at 164. I am wondering what I am doing wrong. I have been blind reviewing, but it seems like I cannot figure out for the life of me how to avoid the same mistakes I have made. Does anyone have advice?