Reflect and Reconnect
This is new. Your child has been away from you and their routine has changed dramatically. Because of this they may feel insecure, overly emotional and push their boundaries more than ever.
Connect with them. Remove distractions. Put down the phone. Step away from the computer. Turn off the television. Focus on your child. Be present. Play with your child.
This helps to remind your child that they are important to you and it really is the best way to deal with negative behavior. While it may feel like you are rewarding them, you are not, you are reaffirming them of their value and your love for them.