Convertible top repairs are easiest when the material used is canvas. Traditionally, most installers want to throw away damaged convertible tops. But they can be repaired using a large sail-repair needle, heavy sail repair thread, a good strong adhesive and canvas which can be glued over the sewn repair seam in the roof. This will then not only keep the seam closed, but it will also help to ensure that the repair remains water and weather tight. Be sure that your canvas repair strip matches the color of your convertible top.
For more info, see How to Repair a Convertible Top