Redesign is not just about visuals. If you change a few gradients/hues and add/remove rounded corners depending on the latest web fashion, then definitely you'r

Redesign is not just about visuals. If you change a few gradients/hues and add/remove rounded corners depending on the latest web fashion, then definitely you're wasting time and money - unfortunately, that's very common patter with companies, specially larger brands. However improving usability of the UI based on some actual metrics and research is definitely never a waste of time. In my experience absolutely every new app needs at least a few UX upgrades after some time, since it's impossible to get every detail of the UI design right from the first go.