Questions about roots

[pauldog28504]

Bought a few orchids at one of the big box stores and one of them had two plants in one pot. I re-potted all of them because the medium was old. The one that had two plants in it one of them is doing great but the other one only had one good root left on it and it was only a 1in long if even that long. Is there any thing I can do to promote new roots quickly.
should i take it out of the moss and just put it in the bag or should i leave it in the pot. I was thinking about making a little green house for this one out of pvc pipe and clear plastic.