If breathing is coming too hard and there is an elevated risk of breathing water, you might be hitting it a bit too hard. We have lost guys who aspirated water under the wrong set of circumstances. **Does anything else you do, hard cardio result in untoward shortness of breath? If so, you may want to see a doctor to check things out. Otherwise, you might want to back off the intensity of kite tricks while conditioning, doing some cardio training with evaluation along the way to see how you are doing. If this is just a question of simple breathhold on impact, which it may or may not be, you might look into a free diving course. Free Diving Instructors International, FII, has a course "Waterman Survival," focused on big wave and tow-in surfers to improve breath hold performance in the context of big wave wipeouts and the impacts that go with them. They work to improve your cardio efficiency through general conditioning, also how to increase oxygen tensions in tissues using free diving breath-up techniques as well as potentially lung air packing techniques to increase the quantity of air you have in your lungs. I would make sure you are good to go in general re:** before pursuing this: http://www.freedivinginstructors.com/fii/course/11
There is a lot more to efficient, safe breath holding in the water than appears on the surface. That is causing a blackout through improper procedures is fairly easy, so it is important to have an excellent instructor. Good luck!