Should I drop / create extensions after upgraging?

Hello all!

I'm on Ubuntu 11.10, using 9.1.4. There was a new package for 9.1.5, and I just finished my upgrade. I make use of the
uuid-osspand tablefunc extensions. What is the expected upgrade procedure for these extensions? A drop followed by a
create?Or is there something else less invasive? 

I can't find any references to upgrades on http://www.postgresql.org/docs/9.1/static/sql-createextension.html, nor on
http://wiki.postgresql.org/wiki/ExtensionPackaging.Where should I have looked to find a reference to upgrading? 

Thanks!
François Beausoleil