You can get an extender to extend the range (surprise surprise) so places that have little or no signal can get some, but the signal strength as a whole? Nope.
Just remember an extender will only extend what it's receiving, so place it somewhere where it can get a good signal.
. How much are you willing to spend? What router do you have at the moment?
nThere's a few here: https://www.overclockers.co.uk/peri...oints-repeaters-and-extenders?sPage=1&sSort=3
Not exactly sure what the best is to go though. How much are you willing to spend? What router do you have at the moment?