Each time you have the same character show up in the main plot, add another detail. Nothing is worse than rehashing the same description over and over. You don’t have to have your character change outfits. It’s not a fashion show. Your goal is to deepen the knowledge and mystery about that characters.
Not all layers are superficial. Your character will already be defined in the reader’s mind by the actions he took in previous scenes. Honor that, but also surprise us. Have him take a different tact. Novels are not sitcoms or comic books. We like characters that evolve and change. Even the secondary characters. This is how you create a journey for your character. One where he’s not the same at the other end.
A fellow writer (I’m looking at you Lee Polevoi) slipped me this gem the other day. I plucked it. Try it out for yourself. Let your character’s subtext bubble to the surface. Give us more than just a cardboard cutout.