Make sure the Peperomia is receiving bright indirect light. Ours received bright, filtered afternoon sunlight, which “tanned” the leaves without burning them. You’ve probably seen this sun-stressed look on popular Hoyas.
If new growth comes in looking very pastel/white or lacking variegation, feel free to chop it off. This type of stress can encourage more variegation. You’ve probably seen this done with variegated Pothos, which respond well to this method when reverting.
Try not to repot too often. We’re not saying to let the plant become so root-bound it can’t absorb water or nutrients, but keeping it slightly root bound can stress the plant just enough that it pushes out more pink. This same logic is applicable with other plants such as Peace Lilies, which like being stressed/slightly root-bound to produce blooms, or Spider Plants, which tend to produce more spiderettes also when root-bound.