If your child is receiving special education services and supports in school, advocacy is an ongoing requirement. I understand, because I did the same for my own child throughout his K-12 years as the social world was a continuous source of challenge and needed skills development.
The single most important thing you can - and must - do is to keep the bar high. It's far easier to keep expectations low and to show progress, yet the reality is that you want your child to be challenged. And sometimes, this means behavioral issues may emerge because he/she is striving for something not easily within reach. It's a difficult trade-off, yet one that's important to weigh as decisions are being made each and every school year.
If your child is not making measurable progress or if it seems as though IEP goals are being easily met, reexamine what's written in that document. Believe that your child can achieve and insist that school programs for your son or daughter accordingly.