Most manufacturers recommend that you do not attempt to repair fitness or exercise balls. Yet there are instances, if the damage is minor and of a specific nature, that they can be repaired for the short term. Repairing a fitness ball is not a permanent fix, but it can be done simply and quickly.
Repairing an Exercise or Fitness Ball
Find out if your ball is burst-resistant. Typically, balls that are smooth, shiny and not textured are not burst-resistant, so don't try to repair them--you could be injured. Burst-resistant balls are highly textured to help them deflate at steady rate instead of exploding.
Fill the ball with the Green Goo, Doctor Ball or bicycle repair substance, and inflate it to the correct size. Maneuver the ball around so that the repair fluid covers the punctured area from the inside. If done correctly, all escaping air should cease, and your ball will be ready for use again in minutes.
If all else fails, take the ball to a tire-repair shop. It can employ similar methods to fix a puncture, but this solution also is temporary.