We are sorry to hear the shock cord has lost it's elasticity. This is a common issue with shock cord poles and can happen at any time. Shock cord is a generic item that can be purchased at most major outdoor retailers. Below are instructions on how to replace it at home. 

DIY Shock Cord Replacement
1. You will need 1/8” thick shock cord and about 1-2 ft. longer than the length of the entire pole for each pole (if you have a 10ft pole get about 12ft, some say a ¾ ratio might be better). Shock cord can be found at your local hardware store or outdoor goods store.
2. Remove the end tip, and the shock cord will be tied in a knot (either on a washer or on the end tip of the pole). Cut the knot and you are ready to remove the shock cord.
3. The most important step to remember is to keep the sections of each pole in the order that you removed them, as you remove the old shock cord.
4. You are now ready to re-string the new shock cord. Remember to re-string them in the same order. Gently push cord thorough entire length of pole, then tie off at one end (either just a knot or attached to pole tip.
5. Then to tension the shock cord, pull out about 25% the total length of the pole in slack (for a 10ft pole pull out 2-3ft) and tie off at the pole end. You can then test the tension and adjust as necessary, the pole sections should seat themselves gently. Remember this is not an exact science, use your best judgement and common sense.
6. Then trim off excess shock cord, and you’re done.
Here is a link to a generic YouTube tutorial if you need some visual help on the process https://www.youtube.com/watch?v=nR-X4IGjK0o