He wiped over his khufoof then remembered that the time for wiping had ended. Should he wash his feet or repeat wudoo’?
Question

                1. Should one have the intention of wiping over the khufoof before starting to do wudoo’, or when he reaches the washing of the feet should he just wipe or wash them?

2. There is a person who did wudoo’ and wiped over his khufoof, then straight after he had wiped over his khufoof he remembered that the period for wiping over the khufoof had ended. Should he take off the khufoof and wash his feet, or should he take off his khufoof and repeat wudoo’ from the beginning?.
Praise be to Allah.
    The intention is not essential for it to be permissible to 
    wipe over the khufoof. So long as the individual put on the khufoof when he 
    was in a state of purity, he may wipe over them. It is not essential for him 
    to form the intention to wipe over them before doing wudoo’; rather when he 
    reaches that point in his wudoo’, he may wipe over them and that is 
    sufficient. 

    Shaykh Ibn ‘Uthaymeen was asked: is it essential in order for 
    it to be permissible to wipe over the khufoof that one should form the 
    intention to wipe over them? 

    He replied: Forming the intention in this case is not 
    obligatory, because this is a matter the ruling on which is connected to 
    whether it is present or not, so there is no need for the intention. That is 
    similar to the case when one wears a thobe: it is not necessary to form the 
    intention to cover one’s ‘awrah with it when praying, for example. So in the 
    case of wearing khufoof, it is not essential to form the intention to wipe 
    over them. The same applies to the intention with regard to the length of 
    time. If a person is travelling he may wipe over them for three days, 
    whether he intends that or not; and if he is not travelling he may wipe over 
    them for one day and one night, whether he intends that or not. 

    End quote from Majmoo‘ Fataawa Ibn ‘Uthaymeen, 11/117 

    With regard to the one who wipes over his khufoof then 
    remembers that the period for wiping over them has ended, if that is 
    immediately after wiping over them, as the questioner mentioned, then the 
    way to proceed is to take off the khufoof and wash the feet only, because in 
    that case there will still be continuity in washing the parts of the body to 
    be washed in wudoo’, and there will be no lengthy interruption between 
    wiping the head and washing the feet. 

    But if he remembers that a long time after finishing wudoo’, 
    then he has to repeat wudoo’ and wash his feet, because with this lengthy 
    interruption it cannot be regarded as a continuation of wudoo’. 

    See: ash-Sharh al-Mumti‘, 1/355 

    And Allah knows best.