After being rejected the first time, is there a testing facility that will let me know if it’s ready now. My car doesn’t get driven much but I put some mileage on it and I don’t want go back until I know the sensors are ready.

Depends on the year of the car, 1996 computer not that smart.

Not ready is not a fail. It's simply not ready. As far as i know you can keep coming back until it either fails or passes.

DON'T take the neg. Battery loose the CAR WILL NOT PASS. go to any auto zone they have code readers they will come out and check it for free. All the banks have to read "ready" if you disconnect the battery everything will read 'not ready' and you will fail for sure. I know this for a fact. It literally only takes the guy at auto zone 1 minute to check for you