(require 'cmuscheme)
(defun cmb-restart-inferior-scheme ()
  (interactive)
  (comint-send-eof)
  ; There is a race here.  Without the sleep-for, the next scheme process
  ; never starts.
  (sleep-for 0 500)
  (call-interactively 'run-scheme) (message "restarted"))

(define-key inferior-scheme-mode-map "\C-cr" 'cmb-restart-inferior-scheme)