If the panoramas are the same ones, where you've just change the withe balance or change something to the image, just make sure the file has the same name as in GoThru (you can check for the file name under Edit, click on the sequence number, top right corner, on a thumbnail) and then upload the file back to GoThru. The new image will overwrite the old image and all you need to do is click on Google->Update and GoThru will auto delete from Google the old pano and publish the new one.
