Nose blindness is the everyday term for becoming less aware of a smell after being around it continuously. A fragrance can still be present even when it no longer stands out to you. This helps explain why a visitor notices your home fragrance immediately while you barely register it.
Step away from the scented space for a while and judge it again when you return. There is no exact reset time that works for every person and fragrance. The point is to stop continuously sampling the same scented air.
If the fragrance is obvious when you walk back in, adding more wax or another product may be unnecessary. Someone entering the room for the first time could already find the scent strong.
For products you can turn on and off, such as an electric wax warmer, use them for the periods when you actually want fragrance, following their directions. You do not have to keep scent going all day just to prove that the product still works.
Switching between different fragrance families may make a change easier to notice, but it does not restore fragrance to spent wax. A fresh citrus scent and a soft woody scent can also feel different in intensity, so do not use that comparison alone to judge longevity.
If a used portion remains faint after time away while a fresh portion of the same scent performs normally, the old wax is probably ready to change. If both are weak, check the warmer and room setup. This keeps 'nose blindness' from becoming a catch-all explanation for every performance issue.