My Internet plan is expected to be renewed on 25th of the month. However, my balance is not sufficient when the renewal is triggered by system on 12:01am, 25th. If I reload on the same day later, am I able to get the Internet Rollover?

No, the on-time renewal refers to the renewal that triggered by the system during early morning (ie:12:01am). Please ensure you have sufficient credit balance before the renewal take place.