Improve what is working

If the site is technically healthy and the structure still fits the business, better copy, stronger proof and a simpler contact journey may be enough.

Rebuild when the foundation keeps getting in the way

A rebuild makes sense when every change is expensive, mobile use is poor, the structure no longer matches the business or security problems keep returning.

Decide from evidence

Look at customer questions, enquiry quality, page speed and the work required to maintain the site. Those signals are more useful than whether the design feels old.