Here is an official source on the Ministry of Home Affairs:
http://www.mha.nic.in/citi.htm
Consider the following extract:
<<
5. Citizenship by registration, (f) a person of full age and capacity who, or either of his parents, was earlier citizen of independent India, and has been residing in India for one year immediately before making an application for registration;
>>
According to this, having previously been a citizen of India, you can apply for citizenship by registration after one year's residence in India.
It's certainly a good idea to ask an Indian official source like a consulate, to make sure of this.