I just solved a grub problem this past Spring. I rototilled the whole area and used a product called "Milky Spore" - basically a spore that infects grubs and kills them leaving even more spores behind. Kind of like biological warfare.
AFAIK, the stuff is safe for people and pets (unlike most grub killers). Presumably it takes a bit longer to work but keeps the grubs away for years. And you can replant your grass immediately. I can report that I have no sign of grubs what-so-ever.