Over the winter I rip all our bikes apart and go through them. I dump all the brake fluid twice a year, (brake fluid absorbs water, hence the brown look of old fluid).
I've always been able to gravity bleed them, but this years my sons TTR 125 would not bleed out. I must have dropped 6 oz of brake fluid and still air.
I had to take a scringe, (I have one I got years ago from EIS and, "push" fluid from the calp to the mastercylinder. Had to do it twice, (make sure there is no air in the tube from the syringe to the calp, or you'll push more air inot the system)!
See if you have a air bubble and, "pump" the lever, you bust the big air bubble into thousands of tiny ones. Air does not compress well, so you get a crappy feel on the lever.
Take your time and make sure you got the air out.
Joe