Since American Girl archived Kirsten before I could get all of her outfits, I had to make my own birthday dress and apron for her, using the patterns from AG. I had purchased the patterns from AG a long time ago when I got Kirsten, but the patterns are available here: American Girl Playthings Dress Patterns.
I lengthened the skirt pattern, but wish I had added even a bit more! The tiny rick rack was tricky to sew. I ended up using a fabric glue to attach it and then sewed it on. When I finished the apron, I didn't have very good light, and didn't realize that I had the bib on the apron on backwards (I lined the top). So, the rick rack on the apron skirt is behind the edge, but on the top, it is on the front. I will probably make this pattern again in other fabrics and see if I can make more improvements to it.