Here's the timing requirement for the exception hold notice:
(ii) Timing of notice. (A) The notice shall be provided to the depositor at the time of the deposit, unless the deposit is not made in person to an employee of the depositary bank, or, if the facts upon which a determination to invoke one of the exceptions in paragraphs (b) through (f) of this section to delay a deposit only become known to the depositary bank after the time of the deposit.
My first reaction was, "How are you going to claim that you did not know the size of the check when it was deposited?" My second was to realize that there could have been multiple deposits to the customer's account or even affiliated accounts and you might not have been aware of them at the time you imposed the first hold.
Assuming you are talking about a single check, no, I don't think you can place the large dollar exception hold after the day of the deposit.
Sometimes, banks do impose holds that do not reflect an attempt to comply with Regulation CC, only desperation.