Can an already registered candidate fill in fresh option at the time of Neet UG 2nd round for Maharashtra state qouta 2019?

Hi Ishika,
No. Choices entered by candidates will be considered final as there is no provision for changing the choices even for the subsequent rounds of Maharashtra MBBS 2019 counselling. Therefore, the candidates were advised to give the preferences according to their NEET 2019 score. Only the candidates who will register freshly for second round (not registeted in first round) are given option of choice filling.
Hope this helps you.

Yes definitely

You have to put fresh choices in round 2 of neet UG counselling

Even if you are allotted in first round you  have to put choices for upgrading. if you didnt get seat fresh choices is required.

https://www.google.com/amp/s/medicine.careers360.com/articles/neet-counselling