Cat prefers sister!?

Hey everybody! I am making this post because i have a couple of questions about my 7 month old kitten. She is sweet, and we’ve had her for almost 2 months. I used to be her favor, she would prefer to sit on my lap and sleep in bed with me. Now, she sleeps with my sister every night, and sits in her lap. She won’t even stay in my lap when I move her there! It actually breaks my heart. I feed her a lot, give her plenty of treats, play with her, and love her. Anyone got any advice on how to make her love me again?