بسم الله الرحمن الرحيم
(Fatwa: 1193/1246/L=11/1437)
You need not spit out repeatedly. Fast does not break by taking in the saliva of the mouth. Your fast is valid. If fasting has become fardh on you then you cannot break it due to exam.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband
