If you ask me that's really just a matter of practice. But I can tell you that you will barely ever need a barre chord on the twelved fret or higher. In a song context you would ofthen only play part of the chord, making the barre unneccessary. Eg. instead of playing the full E barre chord on the twelved fret you would probably just play a double stop and play the A and D string on the 14th fret.