I have a theory as to how she might still be alive.
Yes, she did die in a fight with Kenneth, but Hadrian's Wall somehow brought her back to life, even though she did lose her head. We know that Hadrian's Wall took Kelly's head and that they made Eve from Juliette's body. Since this has happened, I think it is very possible that Hadrian's Wall somehow revived her.
This is just a speculation, so don't hate on my possible theory.