Reassure your young daughter that no one expects her to score as high as a high-school junior on the ACT. She should just relax and do her best. Unfortunately, it's not unusual for gifted programming to end in the middle-school years, but often advanced or honors classes are available for these kids. Taking the ACT will give her access to wonderful summer programs for gifted kids -- you might be receiving more info on that as the school year progresses. Many of these programs are superb.
Things also often improve in high school, with opportunities to take nearby college classes for credit if students have surpassed what their high school has to offer. For your research, try College Planning for Gifted Students by Sandra Berger, published by The Council for Exceptional Children. It's not too early for you to take a look at this book's educational planning tips.