I have to increase the floor level of my bathroom by 1 3/4 inches. I intend to put 1 inch plywood and 1/2 inch for the cement backer board. The tile is approximately 1/4 of an inch. The bathroom floor will then be the same height as the hallway. However, this means that I have to increase the height of the flange pipe by 1 3/4 inches. What is the best way to extend the height of the flange?

Tell us more about the current flange and drain pipe. If its cast or PVC there are "twist-n-set" type flanges that can be used be maybe posting us a picture would help us help you. Oatey 43654 Flange, Twist-N-Set, Closet, 3 In, PVC