I don't know, if I get you right. You mean your preview doesn't update, when you select "spherical cam"?!
I'm not sure if this is the problem, but when I created my VR scene I first tried to get some nice POVs with the regular camera put to a position where the viewers eyes are supposed to be.
Then I switched to spherical camera. The preview stayed the same! No spherical view in the preview window. But when you hit render (lo res with low quality settings for testing purposes - sometimes much faster than waiting for the preview), you get your spherical image.