It sounds as though you are doing the old version of fishless cycling. There is a more up-to-date fishless cycling method which does not have the problems of the old one.
In the old method, ammonia was topped up every time it fell below 1ppm. It is now known that this causes nitrite to go above 15ppm, which stalls the cycle as the nitrite eating bacteria do not multiply above this level, and it makes too much nitrate which also stalls the cycle.
This method usually adds ammonia to 5 ppm which is far more than a fully stocked tank will ever make in 24 hours.
The newer method is designed so that too much ammonia can never be added, so nitrite never gets high enough to stall the cycle and neither does nitrate. It also uses the fact than the filter bacteria do not starve if they are not fed when ammonia drops to zero as used to be thought. It also does not test after 12 hours, the cycle is finished when the tank can clear 3 ppm ammonia in 24 hours.
This method uses 3 ppm ammonia as even this is more ammonia that a fully stocked tank makes in 24 hours
fcmf has given you the link to this newer method. I would drain as much water as you can out of the tank and when you have refilled it, add ammonia to 3ppm and follow the method in her link. I would make one deviation from that method though - since you have already grown some bacteria, instead of testing every third day at the start I would test every second day. Because you have already got some bacteria, the cycle should progress quickly.