I've done re-grinds for my neighbor, who is a leather worker. He uses those standard rounded leather knives. The ones he has are about as thick as what you are working with and they are completely flat on one side with a slightly convex grind on the other. I've gotten the best results on a 2 x 72 belt using the slack area between the wheels, where the platen is mounted. I set the belt vertical, position the blade with the center of the radius up. With my fingers on the blade and the handle in my other hand, I rotate the blade, first to the right 90 degrees and then back the other way 180 degree and then back to center. I check the edge and repeat as needed. I finish the edge on a mouse pad or on softer rubber with a sand paper surface. It took a couple of them to get the hang of it; but when he gets them back these days he is all smiles.
Fred