After updating Slime it’s usually needed to restart Emacs so that the changes take effect, but restarting Emacs is quite inconvenient. After adding the following code into .emacs, M-x slime-reload will reload all the Emacs Lisp parts (CL side should be restarted with ,restart short-cut in the REPL).

(defun load-slime ()
  ;; here should be placed all the usual configuration code.
  ;; like loading contribs and setting variables
  (slime-setup '(slime-fancy ...)))

(load-slime)

(defun slime-reload ()
  (interactive)
  (mapc 'load-library
        (reverse (remove-if-not
                  (lambda (feature) (string-prefix-p "slime" feature))
                  (mapcar 'symbol-name features))))
  (setq slime-protocol-version (slime-changelog-date))

  (load-slime))