Call the local school board or the truancy Dept. There are laws about attending school and they may take it more seriously than CPS.
Children who are on roll at a school but are not in regular attendance. In this case, referrals should be made to the Education Welfare Service, or the school's Attendance and Welfare Officer.
Complain to the school Contact the school to discuss the problem first - most problems can be solved this way. You can make an informal complaint. The school will tell you when they will respond. After they review your complaint, you'll be told the outcome.