This photo was lit with a homemade LED light panel, and I suspect the low CRI of the lighting was one of the reasons that it looks kind of dull. I've white balanced it as correctly as I know how and even tried to use a curves adjustment layer in photoshop to add some life to the colors, but I still think it looks pretty dull. How can I fix it?
I would start with reducing contrast and saturation.
This picture on Facebook you posted in the comment is a bit desaturated, but was also shot using a wide-open lens with a long focal length in a whole other lighting environment. It will be difficult to mimic that look.
As far as I can tell, the problem in this image is mixed lighting, from the LED light panel and light from the window. The light panel is, if I understand and guess correctly, a continuous light source, and hence probably comparable in intensity to the light from the window, depending on the area of the picture. You can see this by the white balance(WB)/tint change on the white wall in the background. If you try setting the white balance with a pick tool, you will get different readings across this supposedly uniform white wall.
For me, this is a problem which is really hard to tackle, since it depends not on the coordinate of the frame, but on the way that light fell on the scene.
Hence my suggestion would be:
use the WB picker tool and get a reading from the wall close to the face of the person in the left. Vary around until you find a white balance that creates the skin tone you'd like. I'd also try tinkering manually with the tint.
Fix everything else with gradients and masks around it.
It will still be a hard task, and probably it will always look somewhat off, because the mixture of differently colored lights is heavy on the subjects face (as soon as one light source has a shadow cast, the other one dominates the WB and vice versa).
Additional tip for next time: Color gels. Get color gels to balance your light source. You cannot create this effect in digital.