Conditioned media refers to media that has been "used" by the cells. It is a great way to increase the concentration of soluble factors released by the cells. For this I would use your normal media, put it on your cells and culture them as usual, then after 24 or 48 hours (depending on how long your normal media-change interval is) aspire the medium, and sterile filter it. Use it on your next set of cells, normally as 10-30% of the whole volume (the rest is fresh media with any additives you might need).