You need a cleaner with enzymes, and be generous in using it. A black light will be helpful in finding every place she has soiled. I'm sorry she has to go back.
Has she been checked for a urinary tract problem? That's a common reason for cats urinating outside of the litter box. Often the cat does not like the litter or the location of the litter box.
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A dog, I have always said, is prose; a cat is a poem. ~Jean Burden