How to iterate a Shader Pass?

Hello. I have a question.

I'm trying to do a flur shader, and i need too "execute" the same shader pass multiple times "N times" (The shader pass take a value "N" and displace the vertex position pos = pos + normal * N;) Is possible to iterate in the subshader? something like:

SubShader{ for (int N = 0; N < max; N++){ Pass{} } }

Thanks! Leo