Urine / feces cleaning suggestions?

cats, 3 littermaid Mega litter boxes.

About twice a month, one or more of my cats has will urinate and defecate on
3 different spots of our playroom. Occasionally, I have obviously forgotten
to empty the litter trays and can only blame myself, the other times the
boxes appear to be fine.
In trying to clean it I have gone so far as to pull the carpet and put it in
the garage where I soaked it multiple times with Simple Solutions and let it
air dry and did the same with the waterproof pad. I then followed up with
the Simple solutions carpet shampoo in my hoover carpet cleaner. From what
little my nose can tell and the black light can see, everything was clean.
Yet as soon as I put the carpet back in more crap and urine stains will
literally appear in the exact same places.

1) Anything I can use besides the Ketone based repellants? They are
horrible inside
2) Any suggestions for cleaning? The Simple Solutions brand doe not seem to
be doing it. I have also tried Natures Miracle for cats to no avail

With seven cats in our household, carpet stain removal is routine, and the
most effective stain-remover we have found is common household peroxide
(3%). After picking up or blotting up (but not wiping up) whatever-it-may-be
with paper towels, we apply hydrogen peroxide to the affected area until it
is saturated, leave it to rest for an hour or more, and then vigorously wipe
the area with a clean, wet, white cotton handrag (purchased in bundles at a
local hardware store). Usually, one round is enough, and to complete the
process, we use a small wet/dry vac to lift the residual moisture. We buy
the hydrogen peroxide in 32oz brown plastic bottles, and substitute a
good-fitting spray-bottle top for the original plastic cap.