Must one repent from the thoughts and whisperings that come to a Muslim during Ramadan, in which he might feel that he intended to disbelieve or break his fast?

These whisperings do not affect the fast or faith, and your dislike for them is a sign of your faith. We advise you to ignore them and turn to Allah Almighty in supplication to divert them from you. Previous fatwas have been issued regarding this matter.