L.T.
When my kids were that age they often refusd to perform when they knew we really wanted them to. Perhaps she knows that her not saying "daddy" bugs you and it is now a game for her? Since she recognizes her daddy and smiles when she sees him she realizes the connection to him and shows her excitement. My guess is that if you back off trying to get her to say "daddy" she eventually will. You can always discuss it with he EI therapist when you get that scheduled.