Im not Boggzy, but nevertheless will provide some clarity.
If you had Khaba researched&purchased, you will keep her (obviously)
If you had Khaba researched, but sold her, you will get her back free of charge
If you had Khaba researched, but never purchased her, you will get her free of charge
If you had Khava researched and then reset her tech tree and didn't researched her again, you will get her free of charge.
So, in other words: it is sufficient to research Khabarovks once (no need to purchase her, also resetting the line doesn't affect this) to get her when the changes will come.
Hope that helps