She vowed to fast six days if her son succeeded, and he did

My wife made a vow upon herself to fast six days every month if her son obtained his primary school certificate. He obtained that certificate about a year ago, and she began fasting from that date. However, she felt regret about it and felt exhausted due to her preoccupation with raising her children and her household affairs, especially during the summer days.
So what is your opinion, may Allah honor you, regarding this vow? Does she continue fasting, or does she seek forgiveness from Allah and repent to Him? It is known that she vowed to fast six days monthly for the rest of her life.
She must fulfill her vow; due to the saying of the Prophet (peace and blessings be upon him): which Imam al-Bukhari recorded in his Sahih. Allah has praised those who fulfill their vows in His saying, Glorified and Exalted is He: [Al-Insan:7]. There is no blame on her if she fasts them separately if she did not intend consecutiveness. If she did intend consecutiveness, she must fast them consecutively. We ask Allah to help her with that and to magnify her reward.
We advise her and other Muslims not to return to making vows; due to the saying of the Prophet (peace and blessings be upon him): agreed upon for its authenticity. And success is from Allah.