Though not a difficult undertaking to repair consider the condition of the rest of the harness components first. I would suggest replacing all the webbing on your harness not just a stitch over. Stitching is easy with a hand awl which you can purchase for about $10. If you don't have the materials readily available in your area try http://www.sailrite.com/
they have always treated me well. They also have a good selection of products for kite repair.