Praise be to Allah.
Giving the child a particular name is something that is permissible. If a person has vowed to give his son or daughter a particular name, that vow is regarded as a permissible vow, and in the case of a permissible vow, the one who made the vow has the choice between doing what he vowed to do or (not doing it and) offering expiation for breaking the vow (kafaarat yameen).
The Standing Committee was asked: I made a vow to Allah that if He blessed me with a son, I would call him Ra‘d after Soorat ar-Ra‘d, so that he would have an Islamic name, and so that he would not go through the stages and sins that I went through. But now the time of my child’s birth is approaching, who is to be known as Ra‘d, but many people have made me afraid to use this name in particular. What is your opinion of it? Please note that I have prayed istikhaarah concerning it several times, asking Allah to guide me, and I dreamt some things that put my mind at rest; for example I dreamt that he memorised the Qur’an quickly. I hope that you can advise me about that; thank you very much.
The committee replied:
What you have mentioned is a vow to do something that is permissible, so if you wish you may give him this name, or if you wish you may refrain from that and give him some other name, and you will have to offer expiation for breaking a vow (kafaarat yameen), which means freeing a slave or feeding ten poor persons, giving each of them one and a half kilograms of food, or clothing ten poor people. If you cannot afford to do that, then you must fast for three days. And Allah is the source of strength.
End quote from Fataawa al-Lajnah ad-Daa’imah li’l-Ifta’ – vol. 2 (10/473)
Based on that, if Allah blesses you with a daughter, then you may either name her Juwayriyah, in fulfilment of your vow, or you may give her some other name that you like better, and there will be no blame on you for that, but you will have to offer expiation for breaking the vow.
For more information on expiation for breaking a vow, please see the answer to question no. 45676
And Allah knows best.