Hmm... it sounds like he probably doesn't mind the spray that much, and continues to chew on objects with the spray on it, so he continuously has it in his mouth. If it isn't working, it probably won't work. Some dogs are unphased by bitter sprays. =/

I would work more on supervision than trying to deter him with sprays. Crate him when he can't be supervised and provide him with a vast assortment of healthy chews. Have a bully stick/pig ear/lamb ear/tendon/etc in every room of your house and when he's going for your furniture re-direct him to an appropriate chewy.