how to create v2 patch

Let's say that following the scheme laid out in
http://www.kernel.org/pub/software/scm/git/docs/everyday.html#Individual%20Developer%20(Participant)
I have produced a patch, submitted it to LKML, received a few
comments, committed appropriate changes to my local git tree,
and now want to submit a revised patch. How do I do that?
If I just run git-format-patch again, it produces my original
patch plus a second one containing my updates, but what I need
is a single new patch replacing the first one.

Thanks,
Tilman

-- 
Tilman Schmidt                          E-Mail: tilman@imap.cc
Bonn, Germany
Yes, I have searched Google!