Yeah but then why did she make Jane her heir?

Condy has to pretty much kill her Heiress every time a new one pops up and threatens her throne. Could you imagine how much easier it would be to have a Goddess of Life serving her every command, never turning against her? Besides she’s a key part of the Repopulation Thing with Humans, either to reign over a planet of both Humans and Trolls and keep TWO species subjugated, or as a back-up plan in case she can’t get the Matriorb from Roxy, at least she can keep ruling over SOMETHING. Even if Human Reproduction is not something she finds tasteful.

Also she may not WANT to die, but you can never exactly predict the turns and twists life will throw at you. Having a back-up is good- And with Jane under her control she could resurrect her if things got really bad, at least once.