Got me, it's your laptop. You'd need access to the antenna on the wi-fi card. If your laptop has an internal antenna the only practical way of doing it would be to get an external wi-fi card that has an antenna jack on it. I ran across a website where someone opened up their laptop, removed the old antenna and modified the case of the laptop to have an SMC connector, but that's not a project for the meek. If you can manage to get a cantenna of the appropriate size on the wi-fi card though it'll increase range in the direction it's pointed massivly. They have a gain of around 12db which is for the decibel illiterate a receiving gain of around 1500 percent if they're done right.
If you don't want to open up your laptop this website has one solution. I personally would be a little more comfortable hacking a USB wi-fi adapter over the laptop itself.
**broken link removed**
Something to keep in mind is that these antennas are HIGHLY directional,.