Why a surviving Yorktown would be repaired

Would Yorktown have been worth repairing if the final Japanese torpedo had missed?

Yes; she could likely return to service sooner than a new Essex-class carrier could replace her.

The answer treats repair as an easy decision if the damaged carrier could reach Pearl Harbor. Yorktown was a capable fleet carrier at a moment when the United States still lacked abundant replacements. Repairing an existing hull is usually faster and cheaper than building an entirely new ship. Her return would bridge the gap before Essex-class carriers arrived in strength.