The daphnia might have died off if the temperature got too warm. If you let the pond dry out and wait a few months until it cools down, then fill it back up with dechlorinated water, the daphnia eggs will hatch and you will get a new colony.
The copepods will also leave eggs in the sediment and they will hatch when the daphnia eggs hatch.
It's preferable to keep single species cultures rather than mixing them. When you get the daphnia going again, make a few cultures with just daphnia and a few with only copepods.