I am presuming your pixie lilies are liliums & not peace lily or any other type not in the lilium family. If so then the best way is to plant...
First, when you say you have a pink bromeliad I am presuming you mean the flower is pink & the leaves are silverish or greyish green leaves. If so...
I would take it to the sink & wash off the aphids. I would continue to spray the plant with the insecticidal soap once a week for a month.
