Upgrade a binary package

[Eric Brunson]

I've been searching the manual and the man pages, but I can't seem to 
find a command to update an installed package to a newer version.  I 
always get a message like this:

pkg_add: package 'expect-5.43.0_1' or its older version already installed

I only find info on "pkg_add" and "pkg_delete" for binary packages, the 
only references to updating a package give directions on how to use the 
ports tree.

Is there a way to update an installed package with a newer version?