You might - and I doubt me she would be terribly pleased, if so! It would be quite rude, no? To return her gift to you by loosing the life she worked to save?

But there are other dangers, too. In my world, only the Enemy dealt in forcing lives back from death's gates, and what you got back was... well. Hard to say how many of the Necromancer's wraiths were warped into what they became by his actions, and how many became that by choice. But the Dead in my world are dangerous, pitya losse, and I can only hope it is not so in yours.