A tad cliched, perhaps, but ...
First of all, I quick masked the girl's eyes into a separate layer for later. Then I stamped out the crack in the concrete and applied some light sharpening. I also took a copy of the pavement in the edges of the photo into a separate layer and applied a little blurring, but I am not sure that it had much effect. Then I used a channel mixer layer to convert the whole background layer to b&w and then added in the layer with her eyes (still blue). I applied a bit more sharpening to that layer and then adjusted the opacity so that the color-mask effect was not too over-egged.
Edit: This probably needs a bit more contrast to give the b&w a bit of presence, so I probably should have fiddled with the levels a bit:
