Not sure that repainting will add value, but it'll probably make it easier and quicker to sell.
You'll be forced to tidy the place, it'll look fresher and more cared for, and light, neutral colours (well, white or magnolia) make the place look more spacious and make it easier for buyers to imagine their stuff in there.
Might make the difference between selling in three days and three months.
(Quite seriously, a friend put in a couple of weeks of effort with his place, and then invited the estate agent in at the beginning of a week. Went on the market on the Thursday: he had three offers by close of business on the Monday.)