What kind of capo do you use? I find that the spring type, like Keysers or Dunlop Triggers, always require retuning, especially on the first two frets. This is because you can't control how much pressure to apply and they pull the strings sharp. I much prefer the Shubb or Paige. You tighten them only enough to stop the buzzing and they need much less retuning.
(You are also not tempted to put them on the guitar head when you're not using them, which I think looks unsightly, especially when combined with an electronic tuner.)