Initally, approval from others (she really wanted to upstage Waverly). She dreams of others heaping praise on her after her performance.
Another thing she wanted was freedom from her mother's expectations. After she fails miserably at the talent show, Jing Mei makes it very clear that she does not want to continue with her piano lessons. She knows that she could never be the piano player her mother wants her to be. Her mother does realize this but it causes Jing Mei pain now she realizes that her mother will never be proud of her.