This is actually a very easy resolution as well as a common question when customers move. I would recommend power cycling both the router and the Slingbox to see if it picks up on the network connection. If that doesn't resolve the issue, the next step would be to hard reset the Slingbox. Below is a link that walks you through how to hard reset the Slingbox:
Let us know if you need additional assistance!
The Sling Moderation Team