What should a worshiper do if they feel urine descending during prayer, whether praying alone or behind an Imam, and then doubt it?

If the sensation of urine exiting is merely an illusion or a whisper [from Satan], then it should be ignored. The cure for such whispers is to disregard them, and similarly, doubt should not be entertained because certainty is the persistence of purity. One should not exit prayer except with certainty that something has exited. If certainty is attained regarding the exit of urine, then it is obligatory to exit the prayer, perform istinja' (ablution for impurities), make wudu' (ritual ablution), and then resume the prayer. If a person suffers from urinary incontinence, they should take precautions and perform wudu' for prayer after the time for it has begun, and pray the obligatory prayer and as many supererogatory prayers as they wish with that wudu'. Abandoning prayer is a grave evil that necessitates repentance and making up for the missed prayers.