Is it permissible to renew the water for wiping the head if the water dries during the wiping?

Wiping the head is one of the pillars of ablution. Scholars have differed on the sufficient amount to be wiped. According to the view that wiping the entire head is obligatory, new water must be taken to complete the wiping if the hand dries during it. However, according to the view that wiping the entire head is not obligatory, there is no need to renew the water if the hand dries after the sufficient wiping has occurred. It is generally expected that the wetness remains on the hand until the wiping is completed. One should not be excessive in this matter for fear of developing obsessive doubts (waswasa).