If I understand your question correctly, your son is eleven years old. What is unclear is whether he is receiving Communion licitly because he has been prepared to do so and has received his First Communion and is now refusing to live out his Catholic faith in daily life, or whether he is a non-Catholic – indeed a non-Christian if he is unbaptized – receiving Communion illicitly.
If he has been properly prepared to receive First Communion, and is thus receiving licitly, I recommend treating this situation as you would if he were refusing to do his schoolwork. You have the right to expect him to live up to the commitments of his Catholic faith while he is under your authority. Being intimidated by pre-pubescent rebellion is hardly helpful to him. He needs a parent who will set limits and expectations in a firm, no-nonsense manner. If you need help in asserting your parental authority, I recommend contacting the Pastoral Solutions Institute or CatholicTherapists.com for a referral to a Catholic family counselor in your area.
If he has not made his First Communion, or if he is not Catholic, he should not be receiving Communion even if he believes in the Real Presence. While you can explain to him the proper procedure to receive a blessing during Communion time (e.g., approach the priest with arms crossed over chest to indicate that one is not receiving Communion), you should be even more firm that he is not to receive Communion until he is properly prepared to do so. Proper preparation includes the commitment to live his Catholic faith.
If he is not yet a Catholic, he is over the age of reason and must decide for himself whether he will accept and abide by the Catholic faith. Until he is ready to do so, I cannot recommend forcing him to join you in private devotions. Prayer and a positive example of Christian holiness will be your best tools to softening his heart to consider Catholicism.