Hi Arnab!

The fact that there has been an addition of seats changes little since there is a proportionate increase in students appearing for the exam as well as marks scored. There will be little fluctuations and the cutoffs may even increase. 

To get an idea of this year's cut-offs, you can look up previous year's cutoffs of the state: https://www.medicine.careers360.com/articles/neet-cutoff-west-bengal/amp

Good luck!