Splicing

For now, increasing a channel’s capacity or taking money on-chain requires closing a channel and takes time. A new proposed feature, splicing, originated from Rusty Russell last October, allows users to coordinate an on-chain transaction to add or remove funds from a channel.

From https://www.theblockcrypto.com/2019/01/18/from-reckless-to-wumbology-lightning-networks-infrastructural-build-out/