Thanks for using our answers forum! If you have a new Slingbox, you will need to run through Setup on Slingbox.com just like you did with the first unit initially. You will just need to make all of your audio/ video connections, connect the Slingbox to your router and then configure your input(s) ie: select your cable box manufacturer/ model and provider.
Here is our setup FAQ page from our support site:
Hope this helps!
The Sling Moderation Team