Recoat or rebuild?
If the foam itself is intact, the answer is almost always recoat. The elastomeric coating is what does the waterproofing — it sacrifices itself to UV so the foam underneath stays sound. A proper recoat every 4–6 years is normal foam roof ownership and adds decades to the system.
Rebuild is the answer when the foam itself has saturated, when there's evidence of long-term moisture intrusion below the substrate, or when impact damage has fractured the foam down to the deck. We'll inspect, document any moisture intrusion with a moisture meter or core sample where appropriate, and tell you honestly which side of that line your roof is on.