What makes you think a UV filter would do anything here?
I'd say the image is a bit underexposed. Next time, rely on the histogram more... I don't really buy into the "it's close enough, you just fix it in post processing" mentality. There's no reason not to nail exposure - at least most of the time.
I'd take the shot into CS3, and tweak the levels. Or, play with it in ACR - adjust the exposure, use highlight recovery to pull back some of the skin glare, and maybe warm the WB a tad...