Hi, I've been travelling in India for 90 days with my husband and our SIM cards have been cut off. Apparently the government request tourist SIMs are deactivated at this point due to visa length. However we have 6 month visas. Has anyone had experience of getting an Airtel SIM reactivated? Or any recommendations of where a tourist can purchase a SIM in Varanasi? Thanks

I found this article and hope it is helpful: https://www.asiahighlights.com/india/sim-cards.

You can call to customer care and by providing the answer few questions as per their guideline. you can get reactive your airtel sim card easily.
But before that, you need to check your call package is activated. If your plan is expired you still can get the incoming call.