Why the same spot keeps getting targeted
Dogs toilet by scent association far more than by memory of "this room" or "this rug." Once a spot has been used, uric acid residue soaks into the surface and continues to signal "toileting area" to a dog's nose long after a normal clean. Even a spot that's been steam-cleaned or scrubbed with regular products can retain enough residue at a molecular level to keep drawing the dog back, which is why remarking often looks like a stubborn habit when it's really a lingering scent problem.
Step one, clean it properly
A standard surface clean isn't enough for a spot that's already been marked more than once. Use an enzymatic cleaner, saturate the full area (not just the visible stain, urine spreads sideways under carpet and into padding), and let it sit for the full contact time on the label. For hard flooring or grout, the same principle applies: surface wiping doesn't reach residue that's soaked into a porous surface.
Step two, change the spot temporarily
While the scent is being fully removed, block physical access to the area for a week or two, a piece of furniture, a baby gate, or simply closing a door works. This removes the opportunity to remark while the enzymatic treatment does its job, and it interrupts the habit loop that's built up around that specific location.
Step three, watch for the warning signs
Dogs usually sniff intently and circle before marking a spot again. Supervise closely near the previously marked area for the first couple of weeks after cleaning, and interrupt calmly (a verbal cue and redirect outside) at the first sign of sniffing rather than after the fact. Rewarding the correct behaviour outside continues to reinforce the habit you actually want.
When remarking is about more than scent
If a dog keeps marking a spot despite thorough cleaning and supervision, consider whether it's territorial marking rather than a toileting accident, common in unneutered males and in multi-dog households, and usually a small, controlled amount rather than a full bladder. This is a behavioural pattern rather than a cleaning problem and may need a broader look at routine, other pets in the home, or a vet behaviourist. Ruling out a urinary issue first is still worthwhile if the pattern is new or the dog seems otherwise unwell, since medical causes can look identical to habitual remarking at a glance.