Don't fret over her retrieving at 15 weeks. Just tease pup with toy, ball, or puppy bumper throw it and build her desire to chase something. The bringing back part comes later. Get Bill Hilman's video, Training a Retriever Puppy. He's a sponsor here so check out his ad on top of this page. If not his, there are plenty of others out there. Enjoy the pup and bond with it. Don't push it.