Don't re-UV the head!

Select the edges that make up the back of the head (mid-spine), and in the UV window, use the cut button (the icon with the pair of scissors). Then select one UV on one half of the head, select the shell (Select -> Select Shell), move the UV's around as a whole, and move the two halves of the face close together. Then select all the UV's that make up the center of the face, and sew them (the icon with the blue-colored stretch of tape).

Hope you read this before you re-UV...XD