You’ve been diligent about closing your bag when not in use to avoid spilling chalk, but all of that opening and closing can eventually wear the cord out! No worries, it’s easy to thread a new cord into the drawstring part of your bag. You need a thin piece of cord (a narrow shoelace can work) and a small safety pin which can fit in the grommet hole.
Make sure to keep track of your cord lock (the little black ball with a spring loaded button that holds the bag closed).
Stick the safety pin through one end of your cord (which should be about 18” long) and close it. Then push the closed pin through the grommet and use both hands to work the pin through the fabric that encloses the drawstring. You should be able to grab onto the pin through the fabric to maneuver it all the way around the bag and back out the grommet. Next put both ends through the cord lock and tie them together in an overhand knot to keep the grommet from slipping off.
Voilà! You have a fresh new cord!
You can prolong the life of your cord by pulling the drawstring enclosure fabric away from the grommet hole when closing the bag. This prevents the cord ends from pinching the enclosure fabric (which would pull the fabric into the grommet hole and cause extra friction on the cord).