Battery change would be the first thing, get the number off the battery and google it, theres websites dedicated to small watch type batterys.
They are not alarm specific by the way, there just like a watch battery as far as i know.
Also another tip, point the end of the remote onto the underside of your chin and then press the button, this makes the range longer because your body is acting like a huge ariel, thats why tvs picture gets better if you touch it( talking about crap indoor ariels of course)