The website redesign vs refresh decision comes down to one question: is the structure wrong, or just the surface? If your pages are organised around what you actually sell and the site is technically sound, you need a refresh — new copy, better imagery, tightened...
If your website is not generating leads, it is almost never a mystery and almost never the design. In practice the cause is one of seven things: the wrong traffic, no clear next step, a buried or broken contact path, slow load times, thin trust signals, no tracking,...