Afaik, only the un-neutered male cats spray their boundary lines.
Cats do not pee on previous dog spots.
You should be ok.
If your female cat is peeing excessively in the house, she might have a serious health problem or the wrong type of litterbox brand is being used.
Some cats do not like certain heavily-scented clay.
I would rent a rugdoctor and go over the carpet again to remove the residual chem-dry in the carpet fibers.
It will be soggy for a day, and might damage any nice wood floors underneath, but it will get rid of chemical dust.