TL;DR
Rehab a Utah well if the casing is sound and you can recover at least 5-10 more years of useful life for under half the cost of new drilling. Otherwise, drilling new gives you a fresh 30-50 year asset and a chance to upsize the casing.
Summary
When does it make sense to rehabilitate a tired well, and when is it time to drill a new one? A clear cost, lifespan, and risk comparison for Utah well owners.