Frontal lisp still after therapy

by Tiffany
(New York)

Hello,

My 6 year old son has been in speech therapy for about 6 months for an interdental lisp with s and z sounds. He does great in the session because he knows he has to focus on keeping his tongue on the bump in his mouth. But as soon as the session ends, he goes right back to sticking his tongue between his teeth when he makes s and z sounds. I am feeling defeated, I am tired of paying the copay for every session 2x a week for the last 6 months to not see much/any improvement in regular conversation. Can someone give me some advice?