If your child is under 16 years old and need to renew his passport, you will need to follow the same procedures as applying for a new minor’s passport. This will involve submitting a completed Form DS-11, evidence of U.S. citizenship for the child, evidence of parental relationship, evidence of parental consent, a recent passport photo, and the appropriate fees.
It's important to note that the process of renewing a child's passport is slightly different from that of an adult's passport.