If the money falls below the minimum threshold (nisab) and then increases again, reaching the minimum threshold once more, is zakat obligatory upon it when it reaches the minimum threshold again, knowing that the initial minimum threshold is still outstanding?

If the wealth falls below the nisab (definition) (minimum threshold) during the hawl (lunar year), then Zakat (definition) is not obligatory on it. This is because one of the conditions for the obligation of Zakat is the passing of a full lunar year on wealth that has reached the nisab, as stated in the hadith (definition): "There is no Zakat on wealth until a year passes over it." If the wealth returns and reaches the nisab after decreasing, a new hawl begins for it. However, if the wealth was acquired and did not fall below the nisab during the hawl, then Zakat is paid on it at the time of its hawl.