I would wait. Our son had tubes at 10 months. He had already experienced hearing loss and had had 8 ear infections. He may need another set (he just turned 2) but our ENT feels that we need to address the underlying issues before having another surgery. Sure, he's had a few ear infections since the tubes, but he also definitely has some allergies that we need to pinpoint (we are currently doing elimination diet for allergens). How was the allergy testing done? Many times at that age, allergy testing is not conclusive - my son clearly has a strong egg allergy, but the tests came back negative. Your son hasn't even had another ear infection - I think you should wait and see if the fluid can resolve itself now that your son is bigger and stronger. The number 1 cause of ear infections in children is a dairy allergy.
I know others said it, but probably you should find another companion for your dog. :( Also, a holistic chiropractor could help too. Other things we have done are Vitamin D3, and children's DHA (Nordic Naturals makes little strawberry flavored balls that our son just loves). I think the vitamins have helped strengthen his immune system. He now gets colds that don't turn into ear infections. Good luck!