Most of the lines from back then are so hard to find! >,<; I've been to the Factoria Mall not too long ago and didn't see any of the previous lines.
I hope you're able to find her!
ETA: Eeeee!!! While I was searching for School's Out Katie and after giving up with no luck, I randomly looked up the Mat Hatter Katie, just for the fun of it and found this:
Since this Katie is the one you wanted, I did a Zip code search (used mine) and they say they're available at:
-West Seattle
-Kent
-Issaquah
-Federal Way
-Redmond
-Northgate
-Woodenville
Hopefully they have her at one of these Targets. If you plan on making the trip, maybe you can call ahead and make sure it is Katie in case they share the same DCPI number with the rest. ^^ I hope you find her!