>952
こんなのはどうですか？
(defun agi (str)
(labels ((agi% (new-old-alist list)
(if (endp new-old-alist) list
(let* ((new (caar new-old-alist))
(old (cdar new-old-alist))
(pos (search (map 'list #'identity old) list)))
(if pos
(agi% new-old-alist
(concatenate 'list
(subseq list 0 pos)
new
(subseq list (+ pos (length old)))))
(agi% (cdr new-old-alist) list))))))
(map 'string #'identity
(agi% '(("1" . "１")
("2" . "２")
("3" . "３")
("4" . "４")
("5" . "５")
("6" . "６")
("7" . "７")
("8" . "８")
("9" . "９")
("0" . "０"))
(map 'list #'identity str)))))


(setq yen "１２３１２３４５６７８９０円")
(agi yen)