ken...this may sound heretical, but i'd suggest going and just pounding on a single route that is significantly harder than just something between 11/12...more like a solid 5.12or .12+...pick a route that you can do all of the moves on (or nearly all, and just missing a couple) and beat the thing into the ground...don't climb all of your routes this way, but just one...
you will find that a.) yes, you can climb significantly harder than you think and b.) your body will become used to a different "standard" and c.) a mental switch will be made...then, return to a style of trying to flash or get routes done in a couple of tries.