Good cat repellent?

[Manako]

Also, how much of a role could age play in this? My cat is 14 years old so he's fairly old.

Cats will also avoid using the box if they have painful urination, thinking that somehow the box is associated with it. Could you lock him in a room at night with the litterbox if its an issue with him not being able to make it?

[Amelya]

Have you noticed any blood in the urine at all? If he's that old I'd probably try locking him in the bathroom with an empty litter box and check his urine to see if it looks okay. Peeing in strange spots can be a sign of a UTI.

[Manako]

If he won't pee in an empty box you can use rice instead. That's how my friend collects samples from his cats when they are sick

[Callisto]

Water bottle

this, throw it at the cat

As a moderator I frown upon 'first'ing threads with old stock memes, but goddamn if this isn't still hilarious