Re registering/Renewing Avast registration.

I have been using Avast Home Edition since the past 2 years.
I have upgraded the AV from version 4.8 to the version 5.0,before the expiry date of the old version.
The Registration page shows the product as Registered,and the same will expire in 23 days.
I have re registered the product and have received a new registration key.
How do I enter the new key into version 5.0,since the registration page is showing as Registered.

Please help

Hi PDoctor,

Approximately 14 days before the expiration date, you will get a pop-up in the GUI warning you that Avast will expire.

On-line registration is very simple and it’s the preferred method for all users of Avast Free Antivirus 5.0 installed on a computer with standard Internet connectivity. To perform on-line registration, follow these steps:

http://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=459