Hello Gautami, of course you eligible for CLAT 2019 entrance examination. Since there is no age limit to apply for the exam. The eligibility criteria for the Undergraduate programme (i.e. BA LL.B) is as follows:

1) A candidate should have secured forty five percent marks or its equivalent grade in his 10+2 examination or its equivalent examination (if he/she is from general/OBC/PwD/NRI/PIO/OCI category). Also, if you are from SC/ST category then you the minimum percentage required is forty percent or its equivalent grade.

2) candidates appearing for the qualifying examination (i.e., 10+2) this year, are also eligible to appear for the examination but they should provide the required documents.

Also, remember that these are the minimum qualifications. 

So even if you have done your graduation you are eligible for this programme. The last date of application form submission has also been extended to April 15, 2019. This year the CLAT 2019 examination will be conducted through an offline mode on May 26, 2019 from 3:00 pm to 5:00 pm. To get more information and updates for the examination visit: https://www.google.com/amp/s/law.careers360.com/articles/clat/amp

But I would recommend that you go for some other coveted university like DU or IPU. Because NLU only provides an integrated degree/diploma. It will take you another 5 years to complete your undergraduate programme.

So, if now you want to go for some other university which provides only LL.B as a 3 year course, then there are plethora of options. Like, Delhi University LL.B entrance examination, Indraprastha University Common Entrance Test (IPU CET), and other universities (private).

You can check for more entrance examinations here: https://law.careers360.com/exams?page=1

All the best!

I hope this helps.