I struggle with the same problem. I worked with my pro on it and she would make me hit balls with only one thought: make sure the club head comes from the inside. She didnt care where the ball went; she just wanted me to feel that angle of attack. We did it for 3 hours taking breaks to chip and put and rest. Whenever I would try to slip some other thought in, she would pull me back and say: the ONLY thing I want you to do is come from the inside.
She is a firm believer in "I can't tell you what it feels like to do it..." So, she tells me what I need to do and asks me for feedback as to how it feels. Once I started coming from the inside consistently she asked me what I was feeling and we used that as the swing thought.
This works for me: If the front of the ball is 12:00, concentrate on hitting it at 7:00 (or the back inside 1/4 or some other variation of that). Once you do that, you will have your own "feel" or swing thought that necessarily makes it really really hard to come over the top.