M.J.
Welcome to my world! The incentive charts really don't work for the older kids. You have to hit them hard with a consequence, like take away their cell phone or ground them.
The sassy and disrespectful talk is age appropriate. I'm not saying to accept it, but it's not unusual. You just have to keep on them, let it know it's not allowed and follow through with a punishment.
I find as summer goes on and we get closer to school starting, my kids act out more. I don't know if it's too much togetherness or what.