Although I'm afraid it might be the most obvious and simple answer, practice! Just get as much time in nets as possible and make your footwork the key thing to focus on, more important even than hitting sweet drives etc, just get your feet moving to the ball on every delivery. I had a similar problem last season as it was my first back after 2 seasons out and the only way to do it for me was repetition until it became natural instinct again.
You could even try going into nets without a bat at all, just pad up and do a session of simply getting your feet to the ball, that'll make you concentrate more, once that's sorted then hitting the ball with a bat will be easy!