Catch-lights are just reflections of light in the eyes. The absence of these reflections makes anyone look dead. Adding them back in is a quick fix.
- Create a new Curves layer via Layer > New Adjustment Layer > Curves. Fill the mask for this layer with black.
- Drag the top-right point (the white point) of the curve graph to the left from 255 to about 180 (the point should now read input 255, output 180).
- Zoom in on the eyes to be fixed. Using a hard-edged brush at 100% opacity, do a light, quick brush of white on the mask, revealing the curve adjustment we just made.
- Adding just a glint of highlight in the eyes adds immeasurable amounts of light.