You use a Get & Put via Vlisp is the easiest. This is a method example make sure you do the Get 1st for the two attribute textstrings then do the put.
Code:
; this is not tested !!!
; update title block rev label by entering
: by AH DEC 2012
(vl-load-com)
(defun updatetitblk ( / plotabs len lay title width limit newstr4 ss1)
(setq bname "DA1DRTXT")
(setq ss1 (ssget "x" (list (cons 0 "INSERT") (cons 2 bname)))
(setq x (sslength ss1))
(foreach att (vlax-invoke (vlax-ename->vla-object (ssname SS1 (setq x (- x 1)) )) 'getattributes)
(if (= "REV_NO" (strcase (vla-get-tagstring att)))
(setq t1 (vla-get-textstring att ))
) ; end if
(if (= "REV_NO2" (strcase (vla-get-tagstring att)))
(setq t2 (vla-get-textstring att ))
) ; end if
) ; end foreach
(setq x (sslength ss1))
(foreach att (vlax-invoke (vlax-ename->vla-object (ssname SS1 (setq x (- x 1)) )) 'getattributes)
(if (= "REV_NO" (strcase (vla-get-tagstring att)))
(vla-put-textstring att t2)
) ; end if
(if (= "REV_NO2" (strcase (vla-get-tagstring att)))
(vla-put-textstring att t1)
) ; end if
) ; end foreach
(setq ss1 nil
plotabs nil)
(princ)
)
(updatetitblk)