You can't just build your network once and check if off your list. You need to cultivate your social capital (a fancy term for the overall effectiveness of your network) over time. The way to do this is to: 1) Re-assess your network; 2) Reconnect with your network; and 3) Reform your network.
Stepping into a much larger role is exciting and nerve-wracking. It requires you to expand yourself - to get as big as the new job. You need to scale your leadership. That may sound good, but what does that really mean? Three things to do: Three tools for you: 1) Set the big picture; 2) Scale your communication; 3) Reshape your network.