Is the oath I took not to top up my mobile credit until my return still valid, given that I intended my return to be on a specific date, and this date has changed?

Based on the intention and purpose of the swearer, if the purpose of the oath was to limit extravagance, then the swearer does not break the oath by topping up the mobile balance with an amount that does not reach the limit of extravagance, especially if the duration of stay is long.