You don't have to re-install anything..Symantec nedpoint doesn't need any license..the license upgrade is only paper work and to keep your Software legit.
No need to make any changes in your environment.
Since you have Multi tier protection license so you will have to update the license key on Symantec mail security Products ( for Exchange, lotus , SMTP ,Domino) whichever you are using.
Does Symantec Endpoint Protection 11.0 require a license file?
http://service1.symantec.com/SUPPORT/ent-security.nsf/2326c6a13572aeb788257363002b62aa/1045d9e1cee1b0ff882573a8005e33fd?OpenDocument
https://www-secure.symantec.com/connect/forums/need-sifmsmse-and-symantec-anti-virus-endpoint-protection-manager#comment-2744871