As you have said that you have AVNRT , ablation in 2003 , again having A-fib , chemical cardioversion
The next step would be DC cardioversion after 4-6 weeks with EP studies to be done again to check for any residual pathway.
It is not possible that a single readiofrequency ablation can solve the problem completely.
You need to start on high dose beta blockers + calcium channel blockers.
Pathways between atria and ventricles are usually more than what we see on EP studies , but a review by EP speciailist after cardioversion would be best plan of action
Hope this helps