Turn Cairine into a vampire again?

[The Fallen Hero]

For the vampire faction in the Dawnguard dlc there's a couple of side quests where you add people to the "family". Vingalmo asked me to turn a women in The Warrens into a vampire a few days ago and I go to him again for another quest today and he gives me the same exact quest. But she's already a vampire so I cant seduce her and feed off her again. So how do I fix this? Help please!

 

[Usulama]

All those vampire quests are radiant, so your best bet is to reload from before you got the mission, and you're guaranteed to get a different one.