If several elementary schools feed into the middle school, your child would not be the only "new" student next year. She would be able to become accustomed to the new school environment along with other students who are having the same experience. Plus, she would develop friendships making the transition to high school easier. And she would have the opportunity to get into sports, music, and other activities that she could continue in high school.
In making this decision, consider if your daughter is ready to handle more responsibility next year. In middle school, students have several teachers and will not have the direction, guidance, and support that elementary teachers provide. Will your child do well in a larger, more impersonal school? Or would she be more ready for high school with three additional years in the smaller, more supportive, elementary-school environment?
If your daughter continues in parochial school until high school, you will need to think about the social consequences of this decision. Will some of her friends be following this path so she sees some friendly faces and doesn't feel totally alone? Can she make new friends easily?
Some middle schools and high schools have excellent transition programs. One of these programs, plus your support, will make it much easier for your child whenever she moves to the public-school system.