That's why God made Quicksave? Sometimes you have to take the L and .... save scumm until you you change it into a W
Also a lot of these dialogues are limited, so you're not able to get all the information they have available, being able to recast Speak with Dead on someone would kind of unbalance that, not to mention you could keep revisiting important corpses as the story progresses.
I don't know what else to say, user error isn't very compelling here to change certain limitations.
