Kara thinks Rachel is pretty neat! She seems to give off this air of just having everything together most of the time (even if this is probably untrue unbeknownst to Kara lmao) and Kara really admires that since she's always been the kind of person to be more a whirlwind of organized chaos.

She's the only teammate that Kara remembers and knows now, so she's especially determined to reforge what must have obviously been an unbreakable bond made of love and superheroism, since as they are right now she can't really say that Rachel's much more than a casual friend/very familiar acquaintance. It makes her sad that they aren't as close as they apparently were in the past because timeless connections are the whole point of reincarnation!!

So really tl;dr she just wants to get to know her better even if that means she has to kidnap her on a mall excursion to do so.