Hello Manasi !

You can try one of  following online coaching platforms for CSIR NET preparation :

1. BioTecNika ( https://www.biotecnika.org/ )
2. IFAS ( http://www.ifasonline.com/ )
3. GATEIIT( https://www.gateiit.com/ )
4. Chem academy
5. Eduuncle

If you want any further information regarding these institutes ,please feel free to ask.

Hope it helps !