If you modify your bid for an IPO but don't accept the latest mandate, the blocked amount won't change. When you modify your bid, you'll get a notification in your UPI app with the latest mandate request. Just click 'Authorise' to approve it. Your funds will then be blocked according to the modified bid. You can accept the UPI mandate until 5 PM on the IPO's closing day.3
For example, a user applies for 2 lots of an IPO. Initially, ₹30,000 (₹15,000 per lot) is blocked. Later, he modifies the order to 3 lots. A new mandate for ₹45,000 is sent to the UPI app. Once he accepts it, only an additional ₹15,000 is blocked, not an extra ₹45,000.