I was thinking the only way to brighten up our walls was to repaint, but I've spent a few days wiping down the walls top to bottom, and they are so much brighter! I take the time to spot clean every week, but this thorough cleaning made a bigger impression of cleanliness. I found that a dampened microfiber towel wrung out with dishwashing soap removed dirt the best. Some of my spray cleaners that I've used in the past were too strong and caused paint to fade, especially on my door frames and wall corners in heavy traffic areas.
I rinsed the towel in clean water frequently and worked from top to bottom in a circular motion. Our walls are especially tough to clean because they are textured with plaster swirls. I use Palmolive dish soap, and this gets all the grubby hand prints, pen and watercolor marks, and other kiddie "art" out of the crevices and off of the wall.
Anyway, I think we'll get another few years out of our wall paint before I need to repaint. I got a good work out for my arms as well!