Router Repeaters-which one works?

We have a desktop computer set up with a d-link wireless router DIR-655. Our house is over 3000 sq feet and our lap tops in the house can not get access to our network because of low signal. I was told we needed a router repeater. I am not sure which repeater to get or how it exactly will work, where to plug in..etc. Any advice/help would be greatly appreciated. Thank you!!