If you have registered for Round 1 of counselling for Neet all India counselling then you don't need to register again for Round 2 of counselling. NMC has released the dates for filling your choices for Round 2 of counselling and you have to login to your MCC Application using your passwords and all that where you can re arrange your choices if required. As per the schedule released by the authority, choice filling and locking for round 2 will be held from November 20 to 24, 2020. You need to fill in your choices properly. Usually top ranked medical Colleges should be in the top positions. To get complete list of all colleges you can get based on your rank use this link
http://medicine.careers360.com/neet-college-predictor?icn=QnA&ici=qna_answer
Also check our this link for all details on Neet all India counselling
http://medicine.careers360.com/articles/neet-counselling
And if you wish to choose free exit which is available after round 1 of counselling, your amount will be refunded once the entire counselling process gets over.