Choose some coordinating bias tape.
Cut four 10″ pieces of bias tape and tie a knot in the end of each.
Place a washer under the toe hole on the bottom of the flip flop.
Thread one piece of bias tape through the hole. Then thread the next piece through the same hole. Pull tight and trim the ends of each knot.
Place one washer under each of the side holes and thread the bias tape in through the top.
Try on your flip flop and pull the bias tape through so it fits perfectly. Tie a knot in each piece to hold it in place and trim the ends.
Use some super glue on the end of each knot to keep hold it in place and to keep it from unraveling.