I was able to find several references that claim that the Indo-US treaty provision is limited to five years:
Here it says this (on page 20):
Generally the treaty exemption for students is limited to the first
five calendar years that the international student is in the U.S.
However there is no set time limit for students from Belgium,
Bulgaria, China, The Netherlands, and Pakistan.
However, I couldn't find any specific time limit neither in the treaty nor in the technical explanation. The explanation says:
Thus, for example, an Indian resident who visits the United States as
a student and becomes a U.S. resident according to the Code, other
than by virtue of acquiring a green card, would continue to be exempt
from U.S. tax in accordance with this Article so long as he is not a
U.S. citizen and does not acquire immigrant status in the United
States. The saving clause does apply to U.S. citizens and immigrants.
However, the treaty explicitly says this:
The benefits of this Article shall extend only for such period of time
as may be reasonable or customarily required to complete the education
or training undertaken.
The reason for this last paragraph is to ensure that you don't artificially prolong your student status, and the 5 year limit may come out of the interpretation of this specific paragraph.
Similar paragraph exists in the US-China treaty, and the explanation for that treaty says this:
These exemptions may be claimed only for the period reasonably
necessary to complete the education or training. In some cases, the
course of study or training may last less than year. For most
undergraduate college or university degrees the appropriate period
will be four years. For some advanced degrees, such as in medicine,
the required period may be longer, e.g., seven years.
Based on this, it is my personal impression that if you're an undergraduate student and studying the same degree (and not, for example, finished your BA, and started your MS) - you are no longer eligible for the treaty benefit.
But I suggest you ask a professional (EA/CPA licensed in your State) for a more reliable tax advice on the matter. I'm not a tax professional and this is not a tax advice.