Sorry to hear. I've never kept dwarf gouramis myself, mainly because of this seemingly inevitable disease with imported stock. Here's what Neale Monks on WetWebMedia says about restocking:
"Under no circumstances buy another dwarf Gourami unless you are 100% sure it is locally bred. Even then, it is possible the virus could remain in your aquarium and infect the new fish. The best thing to do is avoid the gouramis sensitive to this disease (dwarf gouramis plus the various hybrid/varieties like "robin" and "neon" gouramis). Instead stick with hardier, look-alike species such as Colisa labiosus and Colisa fasciata."
Also, for those reading, some additional comments about DGD:
"Dwarf Gourami Disease, a viral infection without a cure that infects a large proportion of commercially bred Colisa lalia (including all the varieties: powder blues, reds, Neons, etc.). The problem is that virtually all mass-produced dwarf gouramis are exposed to the disease because of the very low standards of hygiene used by the fish farmers in Southeast Asia. The only "cure" is to get people to stop buying the **** things so the breeders stop producing them. But capitalism being what it is, there are always enough people out there who haven't heard about Dwarf Gourami Disease, so our friends on the fish farms crank out more of these disease-ridden animals. But do not, under any circumstances, either transfer livestock from this tank to another with Dwarf Gouramis, or else add more Dwarf Gouramis hoping to "try again". They will die, as sure as God made little green apples. I really can't say this strongly enough: DO NOT BUY DWARF GOURAMIS!!!! Remove and humanely destroy the infected fish. Nothing else helps. The symptoms are consistent: first a loss of vitality and appetite, then shyness, then bumps, then sores, then obviously bleeding on the skin, then death. If you want a small Gourami species, my recommendations are Colisa labiosus and Colisa fasciata."