I don't know if you have tried this, but it has worked for me in the past as well as all of my friends (which is only 3 people by the way). Find a piece of road that has good spots to turn around so you can section off about 2 miles. Ride this section back and forth (3rd gear turns work really well) paying close attention to your lean angle. Don't use the breaks or gas it really hard just practice getting the cornering spead a little higher. This works best if you really know the road, as if it was part of your favorite track. Go slightly faster in the turn, to the point where you can feel a little uncomforterble but know 99.9% that you will make it. Keep going that speed until it feels good, then go a little faster. As long as you have checked the road for slippery spots ect, and your not charging in too hard and are keeping a pretty smooth steady speed you should be able to keep increasing your speed until your knee hits, or your drag a peg. The trick to this is finding the right part of road, you don't want to be trying this on decreasing turns, they need to be constant radius. I know that I am comfortable enough to try to go faster if I can look at my speedo easily, which is another reason to only do this on constant radius turns.
Also, if what if limiting you is a feeling based on an SR I have found that if you do other things that evoke the same feeling, and get comfortable with it, the feeling gets pushed back farther on the bike as well. I use my mountain bike for this. I noticed that the same feeling I get when I start to lose my front wheel on the motorcycle is that same sinking stomach feeling I used to get when I started mountain biking and thought something was too steep to go down, or did a wheelie too far and knew I was going to fall on my back. To over come my fear of the losing the front wheel on my motorcycle I used to take my mtb out front and purposly do a wheelie that was past the balance point, trying to use the rear break to keep from falling on my back. I didn't notice that this had anything to do with riding motorcycle until the next time I had a loss of traction in the front. Instead of losing 3 to 4 tenths of a second being scared about it, which ususally will get you into the oncomming lane, I just reacted, saving thoses tenths and keeping the bike in my lane. To this day my biggest SRs come from traction loss in the front end of my bike, but getting used to that feeling has made a huge difference in my confidence.
For all I know this advice may be the worst in the world, I haven't yet attended school but I have read the books. I've been riding for 11 year, and going pretty fast for about 8 of them. I credit Keith's books for all of my progress as a sport rider, as well as saving my life as times though his teachings. Some day I want to attend one of his schools, if nothing more just to say thanks for allowing me to do what not many can, and do it safely (sort of). Don't stop riding, I tried that once and hated my self for it!