Low battery won't make the keys "sticky", though if some are unresponsive but have a firm action the batteries may be low.
Take the batteries out first, anyway.
Try cleaning carefully round the keys with IPA (iso-propyl alcohol, from your chemist) on a cotton bud. If you can (without damaging the remote) remove the case, it can be worth cleaning the contact surfaces with IPA as well. Make sure all is entirely dry before refitting the batteries- in fact, what the hell? Treat it to a new set, why not?
If this doesn't fix it- unless you're skilled with multimeter and soldering iron, internal repairs are unlikely to succeed. On a plus note, you can replace most remotes for under 20 quid- Amazon sell a number of them, and there are also specialist sites that sell almost anything. Or you can get a "universal" remote for anything from a fiver up, depending on how fancy you want/need to be.