After tracing the panels, you're going to have to compensate for the shrinkage caused by the stitching, if you just resew them as is you'll end up with a smaller sail, that might be skewed depending on the bias of the original cloth, different thread tensions on the original machine,etc. How much to compensate? Welcome to the core question that separates having ideas about sails from actually making them...
Just for an example, everybody in the hang gliding industry had to go to temperature controlled lofts, if you sewed one half of the sail one day and the other half later, it would be slightly off from the other side, you could never see it by eye, but you could sure feel it in flight as one wing would keep trying to fly ahead of the other one in a way that was hard to tune out...you could also fly different gliders of the same model, and even tuned the same one of them would just fly "wrong" somehow...