I think that if you haven't prepared your kids for the fact that chickens and other small animals are more fragile than humans etc than you did the right thing, especially if your daughter is of the more sensitive sort. (Goodness knows mine is.) However, you have had your wake up call now, and you can't spend the rest of your days running around finding replacement chickens. These chickens will grown and become distinctly different from other chickens in the world, or next time she'll stroke it and notice it's not just sleeping.
You should start subtly preparing them for the fact that chickens do die much more quickly than humans, and distiquishing the difference between humans and chickens life spans. I've been there when a child that age starts to think "If Goldie dies as a baby then maybe a kid can die too for no reason?" etc. Talk about handling them carefully, predators, and sudden unknown deaths. Use what you are reading on here for examples if you need too.
Good Luck! You are a great and loving Dad.
Laney