Check what already works
List the pages that generate useful enquiries or sales, the content customers rely on and the tools your team already knows. A rebuild needs to preserve those strengths. Look at the mobile journey, editing experience, platform limits and any integrations before deciding.
When an upgrade is a sensible start
If the platform is usable and the problems are specific, focused changes may be enough. That could mean clearer service copy, a better collection structure, a shorter form or a small set of new sections. Define the improvement and how you will check it before extending the scope.
When a rebuild earns its place
A rebuild becomes more reasonable when the current structure prevents essential changes, the business has substantially changed or maintaining the site requires repeated workarounds. Compare the effort of improving the existing site with migration, redirects, content review, testing and retraining.
Ask for the decision in writing
A useful proposal explains what stays, what changes and why. It should identify platform costs, content responsibilities, ownership, delivery dependencies and the route to launch. Ask the supplier to explain why the smaller option would or would not work.