Green’s Dictionary of Slang

(US black) a dealer’s fresh supply of drugs.

1975		Sepe & Telano Cop Team 64: A re-up is a term used to describe the condition existing after a pusher has exhausted his supply of narcotics and goes out to replenish his supply from his contact.
1992		R. Price Clockers 8: Other lieutenants stretched out their re-ups by diluting the product.
2002		Simon & Burns ‘The Buys’ Wire ser. 1 ep. 3 [TV script] ‘How much more to that pack?’ ‘50. 60.’ ‘Re-up’s late’.