If i were u, since the current tank is small, keep it running without changes. Set up the new tank and cycle as per normal.
Another method which i personally tried, and since your bioload is so small, decom your small tank and transfer all ls to a container. Fill up new tank with sand, matured lr and use nsw. Dose bacteria and put in your current ls. Dose bacteria daily. The key point is live rocks must be matured and cured.