I currently have tons of domains and their name servers are set to

ns1.foo.com 1.1.1.1
and
ns2.foo.com 2.2.2.2

I've set up a new server at 3.3.3.3 to be my secondary DNS, it's all up and running and all the domains are on there. I've changed the IP address of ns2.foo.com to 3.3.3.3.

Do I need to go through all my domain registrations and delete and re-add the secondary nameserver to make sure it picks up the new ip or will this happen automatically when something somewhere notices the ip for ns2.foo.com has changed. The reason I am asking is becuase when you set a nameserver for a domain you have to give both the name and IP address, and they've all been given the right name but the IP adress 2.2.2.2.

Any advice would be appreciated.

You'll need to change the ip with your registrar for ns2.foo.com.

Yep, did that. Should that be all?

That should be it, you can use www.network-tools.com to test everything.

great, thanks for your help.

I'm moving this thread to the DNS forum.