Building from Subversion - checkout vs. update

Is it possible to have anthill check for a working copy of my project
in the working directory, and if one exists, only perform an svn
update as opposed to a full checkout (assuming that working copy
corresponds to the repository URL I've pointed the anthill project
at)?  It would be much more time- and resource-efficient to update an
existing working copy for each build as opposed to doing a full
checkout.