Boosting and extending wifi signal

I have the Nighthawk MR1000 and has worked well the last several months and recently has many issues with connectivity isues. After many phone calls with AT&T and Netgear (waiting on hold mostly), Netgear has finally decided to just replace my device.  

I live in a rural area where regular internet service is not an option but in some parts of my house the connection just does not reach.  What is the best device(s) and/or recommend options to extend and boost my range?  Can I add a an external router to pass through the mobile hotspot and use booster?  If so, how?

Thanks in advance!