Have a vet check for UTI's just to be safe.
And just because a dog "knows" in your mind that he should potty outside, doesn't mean THEY know that's where they need to potty. I would personally start house breaking all over again. I love crates for this reason. My dog(s) during housebreaking are not allowed outside of their crates unless I am around to watch them. That means if I'm doing housework and can't keep a constant eye on them, they are in their crates.
Start taking you dog out every 2 hours, morning, noon and night. Since your dog is older you can increase the amount in between potty breaks pretty quickly overnight, but attempt to keep it every 2ish hours during the day when they are up and around.
Also make sure you are using an enzyme killing cleaner on where you dog has gone potty. If you aren't using something like Natures Miracle , even if you can't smell the urine, your dog can. Dogs like to mark and go in places where it smells like someone has gone before.
So clean everything with an Enzyme killing cleaner, start crating your dog when you can't watch him, and start housebreaking all over again.
Remember the key to housebreaking is to not allow the dog to have accidents in the house or catch them when they do. This is why crating works so well with housebreaking. Dog's don't like to go potty in their sleeping areas so they will not go in their crates normally. So this will allow you to control when they go potty more often.
Also another little tip, take their water up about 2 hours before bed. That way their bladders are normally empty before bedtime and less after bed potties.
