Not a stutterer myself, but...

Not a stutterer myself, but... My (15F) boyfriend (15) has been a stutterer for the past six years now, and I've seen him steadily improving since we met (two years ago) with some relapses. We're long distance and I was wondering if there's anything I can do beyond talking to him daily to help with his stutter? Edit: we are long-distance (UK/Canada) and I talk to him whenever I can :)