Either charge more, or just don't? If people aren't willing to pay enough for something, to the point that it can't be done profitably without exploiting your workers, that's the market saying it doesn't deserve to get done.

For example, Applebees is on the ropes. People are unwilling to pay enough money for Applebees' food for the company to remain solvent. Does that mean Applebees has an ethical basis to use slave labor to keep their doors open? No! They should just go out of business.