Legend has it there was supposed to be a scene where Angel comes across Kate Lochley working as a whore at the brothel (saving up for her new identity as an assistant DA in New York?) but much like the guy chained to the wall she declines to be 'rescued'. You know what they say about hookers/strippers and their daddy issues? Personally I think that sounds more like wishful thinking for some folks at the old Bronze forum, much like the Dr Who 'Amy Pond kissogram/stripper?' debate, I couldn't imagine Elizabeth Rohm coming back from L&O to film it.
Aside from the casting issues, why doesn't Angel ever check up on Kate, the way he does with Faith?
You'd think that after you saved someone's life by entering their home uninvited, such a miracle might, I don't know, tell you that you two should probably keep in touch? Even an off-screen "oh, I'm 10 minutes late cause I just swung by to check up on Kate," would have been fine. Angel handles so many of his off-screen Buffy adventures that way.
But we never hear a peep about Kate again. Lilah mentions Lindsey every now and then. Even poor Doyle gets a shout out from time to time. Why no love for Kate?