Do these disconnects happen after a period of inactivity on your laptop? Are you closing your laptop then opening it back up? Laptops have lots of power-saving features that turn off devices after periods of inactivity. These features are designed to save battery life. Check out this post:
Scroll down to the section titled "Modify the default power saving power plan".
The other possibility is that you are accidentally turning off your wireless hardware via a button or function key on your laptop. Many laptops have either a dedicated button which toggles the wireless adapter On/Off (there's usually a corresponding LED which indicates the status of the Wireless hardware). On other laptops, wireless can be turned on/off via a Function Key (FN + other key with a wireless symbol on it).
I believe that one of these two scenarios is likely the cause of your WiFi disconnects. Try both and let me know if this helps.