I was assuming you were interested in DIY answers.
I would emphatically and wholeheartedly suggest a Professional Technician, first.
However, you could pull it off effectively with a few basic tools and a good Enzyme Product. Do you have a shop Vac or some other tool you can extract moisture/cleaning agents with?
How much urine was there originally, and how much did you do at the time or afterwards to fix it? Dry blotting?
If you go with a Professional, don't try to get the cheapest you can....you need a SOLID company with SOLID equipment. Truck-Mounted, with proper upholstery cleaning tools, and proper chemicals or enzymes for the job. Expect to pay a minimum fee of $75, to as much as possibly $175-200 depending on how much needs doing.
I will watch for any responses and help out more if I can.
Cleaning Talk - Professional Cleaning and Restoration Forum
A forum community dedicated to professional cleaning and restoration specialists. Come join the discussion about upholstery, displays, residential, styles, scales, reviews, accessories, classifieds, and more!