Hi,
I'm afraid there isn't a patch that will update your free iClone 2.5 to the latest version of iClone4. The normal procedure is first to register your copy of iClone HERE.
Once you have registered, you will find the discount price to upgrade to iClone4 is shown in the Bonus & Upgrade section of your account.
If you find that you can't register your copy of iClone 2.5SE because it is a non-standard version, then you should contact Customer Support who will be able to offer you a price to update to iClone4. Please use the support form below should you wish to request assistance.
http://www.reallusion.com/CustomerSupport/User/QForm.aspx.
Peter
Forum Administrator
www.reallusion.com