See if there is any interference between the router and your laptop. See if there is any wireless phones near the router. Remove any possible wi-fi emitting equipment which does not include the router etc. from near the router and the laptop.
See if there is an huge wall or some other things which are interefering with the signal.
Try to change the channel number, and probably it will increese your signal.
See the router's manual to help you changing the channel number