With the 300, you can change the antenna to help to extend the range.
http://www.ampedwireless.com/products/sr300.html

Range
The Smart Repeater uses advanced Wi-Fi amplifiers to boost wireless reception and performance. The boosted performance is then optimally tuned and paired with two High Gain 3dBi Wi-Fi antennas for maximum range. (Typical wireless devices do not utilize wireless amplifiers and are equipped with no gain 0dBi internal Wi-Fi antennas)

I would check the RSSI of the setup before going that route.
I use inSSIDer 2
http://www.metageek.net/products/inssider/
which installs
and/or
WirelessNetView
http://www.nirsoft.net/utils/wireless_network_view.html

to check the signal strength using the RSST column.

My laptop reads -45 on my router at 6 ft distance. and can not connect with -70.

As noted changing to a direction antenna would be a big help.

Even the 150 with a 7dB or better, antenna would do what you want.