Question : improve wifi singal with a repeater

We have a 3 floor building with a watch guard  firebox X10e wireless firewall/router . The signal on the 3rd floor is pretty weak and we would like to improve it some how.

I've been reading up about a wireless repeater that may improve the signal, but there are many on the market which is best.

There are lots of wired ethernet points in the building is it possible to plug something in to a ethernet point that could boost the signal?

Answer : improve wifi singal with a repeater

the average AP can provide services to 15 devices well, why not put in a second AP on the 3rd floor and spread your load accross the two?