#+begin_src elisp :noexport
(defun my-set-property-at-heading ()
"Function to be called at the beginning of an Org heading."
(interactive)
(let ((el (org-element-at-point)))
(org-set-property "New" (org-element-property "[ ]" el)))))
(org-map-entries #'my-set-property-at-heading)
#+end_src