re-defvar a variable without reloading emacs

[ken]

I've got a defvar'd variable in my .emacs which I want to redefine.  But
rerunning (defvar somevar "someval") doesn't work... according to the
docs, this is the correct behavior.  So is there some way to redefine
this variable without reloading the whole of emacs?

Thanks vielmals.

-- 
"To make an apple pie from scratch,
first create the universe."
        -- Carl Sagan