Resupply
Refill, Restock
noun, verbal noun, の adjective
To take a supplement and allocate it to where it needs to be is to resupply or refill something.
補充 means filling in the gaps when there's a shortage. It's used for things like restocking supplies, replacing what's been used, or adding more staff to meet demand. The goal is to bring things back to a needed or complete level.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
帰る前にプリンタの紙を補充しておいてもらえるかな。
Could you refill the printer paper before you leave?