Hey! 

If you are talking about counselling of NEET, then you candidates who have got a seat in 1st round of counselling can opt for "Free exit" option and then he/she is eligible for getting seat in second round of the counselling.

In JOSAA counselling, if you wish for another round seat, then you must not pay seat allotment fee and not report to the college and can wait for second round of counselling. 

If you can tell us briefly, which counselling are you taking about then only I can brief you with the process of counselling. 

Hopes you do well!