Is it prescribed to repeat al-Faatihah if a person did not focus properly when he recited it in prayer?
Question

                There is a sister who recites al-Faatihah when she prays, then she starts to recite whatever she can of Qur’aan, but sometimes, if she realizes that she did not focus properly when she recited al-Faatihah, she goes back and recites it again, then she recite whatever she can of Qur’aan, and continues her prayer. Is this permissible?.
Praise be to Allah.
      It is not prescribed to repeat the recitation of 
      al-Faatihah in one rak‘ah. If this sister failed to focus properly when 
      reciting al-Faatihah, then she realised, she should focus properly in what 
      is left of her prayer. If she does that, she will soon get used to paying 
      attention and continuing to focus properly, in sha Allah. 

    With regard to repeating al-Faatihah for this purpose, there 
    is the fear that it will lead to waswasah, then she will not offer any 
    prayers until she has repeated al-Faatihah several times. Waswasah is a 
    disease and an evil that one should beware of. 

    It says in al-Insaaf (2/99): It is makrooh to repeat 
    al-Faatihah. This is our opinion as it is the view of the majority of our 
    companions, and it was stated definitively by many of them. And it was said 
    that it invalidates (the prayer). End quote. 

    Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: The 
    words “repeat al-Faatihah” mean repeating it twice or more. 

    The reason for that is that it was not narrated from the 
    Prophet (blessings and peace of Allah be upon him) that he did that. If a 
    person repeats al-Faatihah as an act of worship, there is no doubt that it 
    is makrooh, because if doing so were good, the Prophet (blessings and peace 
    of Allah be upon him) would have done it. But if a person repeats al-Fatihah 
    not as an act of worship, but because he did not do it in the recommended 
    manner, it seems that it is permissible, such as repeating it because he 
    forgot and recited it silently when it is prescribed to recite it out loud, 
    as happens to some imams who forget and recite al-Faatihah silently. In this 
    case we say: There is nothing wrong with repeating it from the beginning in 
    order to make up for what was omitted of reciting out loud. The same applies 
    if one recites it without focus and wants to repeat it whilst focusing on 
    the second recitation; in this case repeating it has a legitimate purpose, 
    which is to focus with presence of mind. But if there is the fear that this 
    will open the door to waswaas, one should not do it, because for some 
    people, if they open this door they will face a great deal of waswaas and 
    when they recite it, if they are careless in one verse they will repeat it. 
    Then if they lose focus when repeating it, they will lose focus a second 
    time, and a third and a fourth and so on, and then things will become very 
    hard on him. 

    End quote from al-Sharh al-Mumti‘, 3/331. 

    And Allah knows best.