I don't know how to put it in the thread but does any of you reach a point where you find that you don't improve after playing your instrument for some years? As if you can't break out of a particular standard of playing? How do you get out of it and get to a better level? Or are you still stuck?

Does attempting an extremely difficult piece help at all?

I've played clarinet for about 6 years now, and have played the Mozart Clarinet Concerto (Rondo movement)... and it does help. For me, once I got to know the whole Mozart Clarinet Concerto, my finger technique and tonguing improved a lot. I'm sort of stuck at this phase right now of just playing absolutely nothing that seems to be worthwhile anymore and not practicing much (yet I somehow still get music down), and in order to get out of it, I'm taking private lessons (starting in 3 hours, actually), even if I can play the Mozart, because there's always some things that one needs to work on.

Playing a difficult piece that challenges you does help you to improve. also trying to develop styling and phrasing helps.

Practice with your ears, and be more critical on yourself than you are now. If you make even ONE mistake (in anything) stop IMMEDIATELY and fix it. Play it, listen to it, sing it, do anything that'll make you play that note/passage perfectly. No matter how small; a section, a few bars, two bars, chromatic passage, large jumps, one "oddly fingered" note-- if you want to be better, than that single note has to, too.

I think what the OP's looking for is not so much higher level techniques, but to expand his/her style. You can't really plateau in technique... just practice cumulatively difficult and pieces. When you plateau in style, you find yourself stuck playing everything in the same tone and before you realize it, you start getting sick of your own playing.

Try out new pieces of very different styles. Listen to different musicians playing the same piece. Try playing pieces you're fluent in with your eyes closed.

What you're aiming for is the intuition to see the best way a song should be played, what to emphasize in each section, and the atmosphere you're setting etc. Now, that has more to do with how you feel about the song, not the techniques themselves. If you have the song figured out inside, the techniques take care of themselves.

In the end... I guess what you're really doing is developing taste.

Thanks for your suggestions. I can play with my eyes close already for flent piece played umpteen times. I guess I will be searching for a wider variety of pieces to play.