Since installing 8.1 Pro, I'm having issues with WiFi dropping internet connectivity .I have uninstalled/reinstalled the device drivers several times, restarted the computer, etc. I can restore connectivity by turning WiFi off then back on, but the connection will drop at what seems to be random intervals.
MY LAPTOP MODEL :LENOVO G 570
Have you tried here?
http://support.lenovo.com/en_GB/research/hints-or-tips/detail.page?DocID=HT072724
and here
Just make sure It is the correct driver for your laptop.
I used the Intel support page rather than the Laptop makes support page.