Could be a number of things, but generally you don't need to bleed the hydraulics if you replace the clutch. If it is leaking then the hydraulics should be replaced. It will all come in one unit that doesn't need to be bled. If you opened it up you probably let air in the system. It will be really hard to bleed at this point.
I am suspecting if the pedal is limp that is what happened. You may have to remove all of the hydraulics and bench bleed it now, but since you put a new clutch in, I would recommend just putting new hydraulics in now.