If you did not get the seat in the previous round then you can go for the other rounds of counselling and you can fill the choices again as per the seats vacant after the previous round. In state quota counselling you can fill the choices with the modifications and you can add the institutes which you have not fillled previously if available. There is no criteria for the choice filling in the NEET counselling. The seat will be allotted as per the marks and the merit you scored.