Calibration is a process that needs regularly doing. TFT screens drift as they age, and LEDs and CCFL backlighting can drift in colour temp as they age too.
It will only really be totally accurate for a few months if you get someone else to do it.
Bite the bullet and get hold of a calibrator of your own.
X-Rite Color Munki or X-Rite i1 Display Pro would be my choices.
Also.. if you calibrate a laptop, you need to switch off anything that dynamically adjusts the screen with ambient light condition, and turn off any power saving options that lower the screen brightness or there's no point.