Expedition is a risk with rewards. It makes sense to have a risk for rewards, and the black hole is just one way of adding risk among the other things that can happen. Is losing a fleet twice in a row really that unfair? You should send your ships knowing you might lose them, or don't risk it if you do not want any ships lost.
If you lost them while sending them on an expedition to save them from an attack, just set the speed to 10% and increase the duration, but make sure to recall the fleet before the expedition reaches the end.