What should one do who vowed to pray Duha and Qiyam al-Layl daily, then broke her vow and wishes to be absolved of it because she does not want a permanent commitment?

If the vow is in the form of a commitment, then it is a nadhr (vow), and it is obligatory to fulfill it, for the Prophet, peace and blessings be upon him, said: "Whoever vows to obey Allah, let him obey Him." And whoever vows to pray Duha and perform Qiyam al-Layl every day, and fails to fulfill the vow on some days, must make up what he missed as long as he is able. The vow does not become void by not fulfilling it. She must pray Duha and perform Qiyam al-Layl every day and night. For Qiyam al-Layl, two rak'ahs at any time of the night are sufficient if no specific time or number was specified.