The villages mentioned by others in their replies are just show pieces. They do use some Sanskrit in communication, which was taught to them by some activists, but I was given to understand that their vocabulary may not be more than a couple of hundred words and they can’t use it except for their routine communications. It’s more like a trained parrot reciting some sentences.
—I have been copy-editing a paper on the Sanskrit spoken in the village of Jhiri. The researcher estimates that of the 600 villagers, 20 have conversational competence in Sanskrit; and (as you’d expect) there is clear syntactic influence on their Sanskrit from Hindi. The revival effort in Jhiri, as elsewhere, is through the work of Samskrita Bharati, although the village has stopped working with them.
Of course, 20 out of 600 is not the impression you get from googling Jhiri. There is a lot of romance to the notion of reviving Sanskrit.