VOA for 15 days, but I booked 16 days in Thailand

I am a Romanian citizen, living in north east China (Changchun). I can get a VOA directly at Bangkok airport for 15 days. But i made a mistake and i booked with my family a trip for 16 days (so 1 day longer). I do not want to have problems for that day. So what do you advise me to do? I could require for a 30 days visa, but Changchun is very far from everything and my child is only 5 years old.
What would you advise me to do?
Thank You!