Xenserver connection refused

I have a simple citrix xenserver 5.6 setup and usually manage it through xencentre through my laptop. Recently I was overseas and not only did my laptop break but also the free 12 month subscription on the server expired. No worry I got a new laptop, loaded up xencentre and tried to add the server like usual..error message saying' connection refused from server'.

Any ideas on why this is happening and how to fix?

If I can at least update the licence I can work around the issue, is there a way of updating the free 12 month licence through the server direct?? perhaps through the command prompt?