Via GNU screen, you'll be able to attach to (or detach from) current running screen session easily. Furthermore, you can also connect to the running lisp instance using your best editor's (emacs?) SLIME interface.
Note that, to be able to do (asdf:oos 'asdf:load-op :swank), you'll need to create a symlink for swank.asd file (which comes with SLIME tarball by default) in your ASDF system definitions folder.
As an example, ALIW project uses swank-daemon to daemonize its web server during system start up and shutdown.