The quick answer to your question is - Yes. The school can hold your grand-daughter back multiple times (over the course of different grades). However, a more important question is whether grade retention is helpful to your grand-daughter.

The National Association of School Psychologists (NASP) has published a position statement (which means that prominent members of the NASP got together, reviewed the evidence, and determined their official "position" on the issue) on grade retention. Dr. Jimerson at UCSB has also conducted a great deal of research in this area, and he has suggested that more comprehensive interventions should be considered rather than simply retaining a child. Overall, the research indicates that students who are held back/retained have worse outcomes academically and emotionally than their peers who were also candidates for retention, but who were promoted. For more on this, see links below.

Thus, the ideal situation would be to revisit the type of environment and educational supports that your grand-daughter has at school. Is she is a special education classroom? What kind of experience does the teacher have with students diagnoses with Autism? Does your grand-daughter have a one-on-one aide? Many students with Autism benefit from this kind of support to help them focus, stay on task, and organize their behavioral reactions.

It may be worthwhile to schedule a meeting with your grand-daughter's IEP team in order to discuss grade retention and alternative supports for her in the classroom. If you are still having difficult with the school, you may wish to contact the local parent center in your state to get addtional advice. I have included a link to a site that provides information on parent centers below.

Warm regards,
Laura Kauffman, Ph.D.
Licensed Child Psychologist
Education.com JustAsk Expert
 http://www.drlaurakauffman.com/