If you are still on the stock radiator, consider yourself lucky. I have been living with a leaky radiator for about 7 years. Just bit the bullet and ordered a Champion 3-row all aluminum radiator and new hoses. Will be replacing in the next week or so.
Repairing a stock Jeep radiator is really not possible.
Try and find the telltale green trail...coolant will leave a green mark usually. I agree that you don't want to go replacing your radiator if it was in fact your fan clutch, or water pump and it was just collecting there. Look at the bottom of the lower hose too.
If you do end up replacing the radiator I'd go with another OEM. There are lots of threads on which is the best radiator but remember, how long did the original last?
That's the same place mine was pooling up and it was the radiator, it had been leaking for 2 or 3 years and I finally got sick of it and replaced it with another one from jeep, the first one made it 175,000 miles until it got changed it.