Over time, it is inevitable that your hardwood floor will become scratched and dull from general wear and tear. If your hardwood floor has a polyurethane finish, it can usually be recoated without having to sand the entire floor first. Recoating is suitable if the floor is only mildly scratched and worn, the finish has not worn through and it does not have a buildup of wax or other chemicals - these will create adhesion problems and cause the floor to reject the new finish, resulting in peeling and flaking.
Recoating is a simple process that involves a thorough cleaning and scuffing (light sanding) to the wood floors' last applied layer of finish. Then a new fresh coat of finish is applied. Recoating will revitalize the shine and get rid of any mild discolorations that haven't penetrated the wood. It rejuvenates your wood floor and extends the life of its protective finish layers. It is best to recoat your floor while it still looks good. This will prolong the life of your floor and reduce the number of times it has to be refinished. Recoating can be done in a day.