Do you mean the exterior of the house, or the interior? If you mean interior, you can always swap items out for new ones by mailing them to him or waiting for him to request that you give him something.
If you mean exterior... There's not a lot you can do about it. D;
There are lots of factors for deciding if you should keep him, especially since you want other villagers. Do you have another smug villager in your town? If you don't, I would consider keeping him and letting someone else move out. Unless you're not a huge fan of the smug personality, of course. It all comes down to balance and preference in the end.
Good luck making a decision! o v o