i make jean shorts the put the ends through the paper shredder so there's like 6 inches of solid fringe. if i get bored i go into the woods, drink some ayahuasca, and bead the fringe with my shaman friends.
Get a wire coat hanger, unbend it so its straight (or slightly curved, doesnt matter). Feed that through the hoodie where you want the string. Then use pliers to bend the end into a loop, knot the drawstring so the loop holds it, and then pull the hanger back out. Viola! Your hoodie has new life.