AutoCAD Visual LISP / AutoLISP :: Reactor - How To Change Xdata Length If Line Is Modified

I need a Reactor to Modify Xdata - Length - contained in Line Object if this Line is modified (stretched, breaked, trimmed, etc).The routine need to verify if Line contain Xdata and modify it (and works with multiple selection).

I tried for long hours, but without success. I tried to create a list of entities while the reactor is applied, but doing so need another reactor to change these entities after the first Reactor works.The codes I used are below:

{code}
;If it just 1 string only you want to add
(defun add_xdata_str (e a v);;;EName APPID String_value
(and (not (tblsearch "APPID" a))
(regapp a))
(and (= (type e) 'ENAME)
[code]....