Sorry I must have missed that one. Or maybe you were asking how long to cure a medical condition? If that's the case it's impossible for me to guess. The best effects healing wise through fasting are always from long term fasts and if it's something very serious then the aim should be to fast to completion- to the complete cleaning of the body and return to hunger. Otherwise unless you find someone who has fasted with your condition whose experience you could use as a yard stick, the only close to sure way to get an answer would be to consult an experienced fasting doctor about it.
How many times you've fasted before doesn't really come into it as a rule. First time fasting is not a contraindication for long term or complete fasts.