My 8 year old neutered male cat is a "sprayer". He's a BIG , 20 lb. alpha male....(his nickname used to be "Killer" or at least that's what the birds called him!!)
He sprays in the spring time or if I bring a new piece of furniture into my house!( grrrrr, bad kitty, bad!) LOL.
The vet has given him a shot to help him stop it. It hasn't worked yet but I'm hopeful. So, there is a shot if you can't stand to keep cleaning and cleaning and cleaning........hope that helped alittle! Good luck!