Is it necessary to replace the handkerchief that isolates drops of urine from clothing before each prayer, and is it necessary to repeat ablution if the prayer is invalidated or to perform the regular Sunnah after the prayer time has begun?

The summary of the fatwa (definition) is that there is a difference of opinion regarding the renewal of ablution (ta'sib) for every prayer, and the most correct view is that it is not obligatory. The ruling for a person afflicted with urinary incontinence ( سلس ) is to perform ablution after the time for prayer has begun and to pray with this ablution as many obligatory and supererogatory prayers as desired until the time expires. It is not necessary for him to renew his ablution unless another impurity occurs.