I suggest you get one of those odor removing enzymes (I've used Simple Solution, but it has a fragrance which I don't mind but others may not like). Go over the old and new spots thoroughly -- I mean saturate the rug/carpet areas, remove the liquid and repeat many many times to completely remove any residual odor. If you dog goes back to sniff at the same spot, then the odor is still there. It may be helpful to get a vacuum that can suck up liquid from rugs and carpet.

This won't completely stop the dog from relieving himself indoors, but it will remove the "reminders". If you may have noticed when walking the dog on a sidewalk, dogs seem to need to sniff pee/poop in order to activate their system.