My baby who passed as soon as she was born was alive again

I had a dream of my baby girl that was born to early and passed. In my dream she came back to life and I was amazed and so happy that she did. She was a few months old and so happy she was smiling and giggling. I was holding her, cradling her, and I kept looking at her and comparing her features to her sisters and telling her father how much they looked alike. I was so excited to have her back, and also afraid to to lose her again. I laid her down on the sofa, stood up, and turned around to pick her back up and she had completely disappeared. I just felt complete sadness, then I woke up. Any ideas on what this could mean? This was my first time dreaming of her and she passed 15 years ago.