I had the same problem. A fellow bowler said I needed "contact cement," but I could not find anything that met that description in the store.
I ended up getting one called "Loctite," which said it was for vinyl, fabric and plastic."
I figured this would work because I was glueing the fabric (non-velcro) side back onto the plastic sole. The glue worked great, and it helped my problem a little, but the problem I had was that, even though I glued it back together, the velcro side of the sole was no longer sticking to the shoe.
So I had to replace the sole with a new one and that solved my problem.