When the governor vetoes a bill or by veto strikes or reduces an item in an appropriation bill, during a regular session of the legislature, the legislature shall proceed to act in accordance with art. II, sec. 16, Constitution of the State of Alaska, as it is implemented by the rules of the legislature. A bill vetoed after adjournment of the first regular session shall be reconsidered by the legislature sitting as one body no later than the fifth day of the next regular or special session convened during that legislature. Bills vetoed after adjournment of the second regular session shall be reconsidered by the legislature sitting as one body no later than the fifth day of a special session of that legislature, if one is called.