Yes. Practice. On one hand I'm trying to be a bit of a smart aleck. On the other hand, I'm being serious - the trumpet embouchure is not something that develops overnight, and I'm not surprised to hear that you are still having issues after a couple of months practice. Story time.... (yeah yeah, I know - but there may be something relevant to come out of it.) When I left the Army band program in 1999, I didn't touch my horn for about 18 months. This was after playing as part of my job for 10 years, which came after my initial trumpet development between 5th and 12th grade, so about 18 years altogether, and some of it doing some pretty fair playing - not trying to brag, but I was a pretty solid player. It is what it is. In any case, 6 months into my comeback after a 18 month hiatus, I was only then feeling like my chops were getting back to a point where I had regained some of the consistency I'd lost in the 18 months I had been away from it. I don't know what level you were at when you stopped playing, but I do know that 10 years off the horn is almost worse than coming to it from the beginning - worse, because you know what you used to be capable of, and let's face it, adults aren't always the best at being patient during redevelopment, where a kid is just blown away that they are making any kind of sound at all. Give it some time, don't force it, and keep working it. It will come, but there is no trick or sage words of wisdom that will impart to you the insight to improve your range by leaps and bounds in a few weeks. It's simply going to take a lot of time in the woodshed. I think one of the best quotes I have ever heard in regard to diligent practice came at a percussion clinic I attended. The clinician talked about his early days of college and asking his percussion instructor how to improve his snare roll. He was hoping to learn some trick or secret that the professor had up his sleeve. Instead, his instructor said, "if you want to improve your roll, then roll - 10 minutes a day, every day." There are some good tips on here though - one thing I have always used to refocus my chops is to work articulation. Lots and lots of tonguing, especially legatto and multiple tonguing. The chops have to be focused and the air has to be moving right for you to do those well, and a side benefit is better sound, better endurance, more control, and easier upper register. Another thing I used to work on a lot, especially back in my Army band days is what VB suggested - I used to do long tones, starting as soft as I could, crescendoing to a solid forte, and then bring it back down to a whisper, as controlled throughout as possible. Keep in mind, I'm as a much of a hack as any player out there - somehow I manage to continue to gig and get paid, but I'm by no means anything other than a fair weekend gigging player.