One thing you might want to think about is relaxing. I find that when I am going above 180 (and I am pretty short) it’s usually because I’m tensed up. In Chi Running you depend on your legs for momentary support between strides, NOT for propulsion. Going over 200 you would be depending on them for speed, and I am guessing you would get fatigued quicker. Most elite distance runners go at a cadence of 180 - that’s why they can go the distance.
Anyway, check that you are allowing a pelvic rotation, that your arms are swinging freely, and not driven by your shoulders, and allow the ground to take your leg back, which will take your hip back (giving you that pelvic rotation). Use your lean for speed (only takes 1” to go faster with each gear, so don’t overdo it!). And any tension you feel in your arms, legs, hips and shoulders - direct it back to your center. Make it a practice to see how much you can relax while maintaining good form. Let us know how it goes.
Certified Chi Running and Chi Walking Instructor