Whenever a retail installment contract by its terms permits the inclusion of additional goods purchased after the original agreement, and such goods are so purchased and the amount due on the new purchase is combined with an unpaid balance on any prior purchase so as to permit the retail seller to retain title to or reserve a lien upon all goods under the combined agreement, the retail seller shall, at the time of the additional purchase, deliver to the retail buyer and attach to the original agreement:
N.J.S. § 17:16C-28