B"H, 17 Nissan, 5716.
Brooklyn.
Haraha"ch iy"a nu"n oseik b'tzt"z Menachem Zev HaLevi Gringlass
Shalom u'Vrachah!
Regarding publishing an additional new booklet beyond what is already in print—it appears this is not appropriate at present. Especially since, for now, I have not found in Divrei Chassidus any discussion regarding haircutting, etc. (aside from what is printed in the section of Maharid, even though I am certain its foundation is in the writings of the tzt"z).
Summary
The Rebbe advises against printing another booklet at this time due to a lack of clear sources in Chassidus on the topic of haircutting beyond what has already been published.