I got tired of the saggy door cargo netting that no longer usable. Here is what worked for me and probably will work on other saggy cargo netting throughout the car.

Here is what I did:

1. I pulled taught the upper elastic cording
2. I gathered the ends of the cording an passed a needle and thread through both cords. I took the thread, tightly wrapped it around the cording then securing wrap with several stitches.
3. Tacked the excess cording to the inside of the cargo netting.
4. Now, the cargo netting has spring to it and looks new!