CJ,
If she was bitten on the leg (especially lower leg), she'll probably be fine in a few days. The real concern with a copperhead bite is if the bite is near the neck (swelling can close the trachea) or heart (if venom gets in bloodsream).
One of our labs was bitten on the nose by a cottonmouth. His whole head was swollen for a few days, but he was fine after a trip to the vet.
Of course, it all depends upon how much venom was injected. If I recall correctly, copperhead venom is slightly less toxic than cottonmouth venom all other things being equal. Labs are resilient critters. Keep us posted on how she does.
