I have taken some money out to give for zakāt. However, I can no longer find the money. Do I need to pay zakāt again?

Answer:

Zakāt is considered fulfilled once the money reaches the poor. Based on this, your zakāt is still outstanding. The money you have lost is considered yours, and therefore, whenever you find it, you can keep it.[1]

Allah knows best

Ibrāhīm ibn Muḥammad

[1] قال الحصكفي: ولا يخرج عن العهدة بالعزل بل بالأداء للفقراء (الدر المختار: 2/270)
قال ابن عابدين: فلو ضاعت لا تسقط عنه الزكاة ولو مات كانت ميراثا عنه (رد المحتار: 2/270)