I'm no expert, but you can either map the shader with a reflection map...

....but I'd try to create an cube environment, and map it with at least four images (four sides), so that the shader picks up this environment in its reflections.

I have never tried to do this myself, but maybe this helps.

edit: You probably have to adjust the reflectivity value to get get this to look the way you want. (could be you dont see the reflectivity at first, I think lowering the reflectivity to a little over 0 will help in that case, full reflectivity may flood the shader with light I think)