Here's a little trick once you've done the conventional bleed. Mine was done and still had air in it. I was advised of a trick that can work many times: Engine off, slave master cylinder full but top off. Pump the clutch maybe 10 times quickly then hold it the last time. After holding it about 5 minutes, slide your foot off the clutch and let it pop up on it's own. With luck, air in the system will have worked up into the line and the pressure will push it back into the master. You may have to do it a couple of times but it did work for me.