pp-this-sexp.el

(defun lisp-reinsert-as-pp ()
  "Read sexp at point, delete it and pretty print it back in."
  (interactive)
  (let* ((buf (current-buffer))
         (pp-sexp
          (replace-regexp-in-string
           "\\(\n\\)$"
           ""
           (with-temp-buffer
             (let ((bufname (buffer-name)))
               (pp-display-expression
                (with-current-buffer buf
                  (car
                   (read-from-string
                    (replace-regexp-in-string
                     "\\*\\(.*?\\)\\*\\(<[0-9]+>\\)* <[0-9:.]+>"
                     "\"\\&\""
                     (save-excursion
                       (buffer-substring-no-properties
                        (point)
                        (progn
                          (forward-sexp)
                          (point))))))))
                bufname)
               (buffer-substring (point-min) (point-max)))))))
    (kill-sexp)
    (insert pp-sexp)))

nice :)