I wouldn't worry about them killing her off as she is apparently very popular and also she reappears in the Gotrek & Felix novels later on. The entire Ulrika trilogy takes place between the end of Vampireslayer and the start of Manslayer in that 20ish year period where G&F are off around the world seeking something... anything... that is actually capable of killing the Slayer. During this period they apparently visit Araby, the Southlands, Lustria, Cathay, the Ogre Kingdoms and Ind too before returning to the Old World in Orcslayer. I believe some of the stories in the upcoming Anthology will be set during these travels.