Try this.
As you are about to enter a corner, shift your butt to the inside of the corner on the seat. By moving the center of gravity inward, the bike stays more upright in the corner, or rather gravity helps to hold the bike in the corner more than it does if you don't shift over. Practice with your riding partner too, so they understand why you are shifting your weight.. it's safer! ..honest!! I picked this up reading Total Control, a book on riding technique.