there are no secrets man. at least not some esoteric epiphany.. just deeper insights... nothing mystical about having a BB.. the belt (should) signify you have physically and mentally internalized the basics of the system, and are now ready to "do" the art rather than practice. understanding and knowledge can come at any level
you've already attained your black belt. branch out, learn a new martial art.. maybe some martial revelations will come to you if you feel you've hit a brick wall. cos the closest thing to "secrets" you'll find will come directly from the highest people in whatever system you (general you) study.
best of luck finding what you seek.