I suppose that not letting the dog on the sofa is not an option at this point?
Since I, too, love to cuddle with my dog on the sofa (and she loves even more to curl up on the sofa without me), I will share a tip I read in The Bark magazine — rubber gloves. No kidding. Rub the sofa with your rubber-gloved hands. You’ll only feel silly for a few seconds. Once you see how much hair comes off, and how easily, you will either be appalled at the amount of hair on your furniture or delighted with your newly clean sofa. I just vacuum up the hair tufts as I produce them. Easy!