Have you tried any of the courses?
http://www.chess.com/chessmentor/courses?page=1
You can use the Tactics Trainer in unrated mode, if you can do so in the Chess Mentor I recommend doing the hard ones that way and going back over them until they're not so hard. The hard ones may very well be hard because they're covering your weaknesses. I've found CM frustrating at times but overall I think it's well worth the effort. And don't forget:
If at first you don't succeed, you may have already reached your level of incompetence. Dr Laurence J Peter
Just kidding!
So I have completed alot of lessons right on Chess Mentor, so I have a highish rating. But now, the lessons are getting too hard for me and their not fun anymore, or educational. I don't really wanna reset my stats either though, any thoughts?