Err, charge it?
Learn better battery care habits?
I recalibrate every 1-2 months. i'm certain my battery care habits are better than most. that's just ridiculous though - to jump from 100 to 42.
Calibrating doesn't do anything good for the battery, it just makes your count more accurate. Battery care habits include limiting the number of cycles running through the battery, not always using it while plugged in, draining it through natural usage etc.