Bringing buck and doe back together after a litter

I acquired two rabbits last May (2009). They grew-up together, so there were no introduction issues. The male appears to be something called a Silver rabbit and the female is unquestionably a Holland Lop. We let them live together. They got on VERY well until shortly before she "threw" a litter. The morning after the babies came (I didn't know she was pregnant), I found her attacking my buck and him defended himself. We put him in a separate cage and had him castrated. They have been able to see each other the whole time. The babies are nearing 4 weeks old (and are eating the pellets, hay, and veggies wonderfully), but when I try to reintroduce my buck, the doe first bows down as if submitting, they sniff each other, then she attacks the buck. The adults just tear each other up, while the babies run and hide.
   
Will I have to reintroduce them as if they were strangers? Do I wait? Perhaps my doe still wants no other rabbits there? Or hasn't regained her "female" identity-feeling? I can't afford to maintain two cages forever and don't really want my buck alone for the entire winter.

You should always keep the male away until the babies have left, maternal insticts make the doe very protective of her young.
   
When the babies have all gone allow the doe some time on her own before reintroducing, this will have to be done the same way as if they were strangers but should be able to be done slightly quicker.
   
Hopefully she will still recognise that he is her companion and settle back in together.
   

How old are the babies when they 'leave'? Mine are 4 weeks old and have been sleeping outside and eating out of the food dishes for a week now.