Hello aspirant.

If you have qualified in JEE mains examination in January attempt , but if you haven't qualified in April attempt , then you are eligible to write JEE advanced examination. NTA (National testing academy) will consider best of two score ,it will ignore lower score.

For more information refer

https://www.google.com/amp/s/engineering.careers360.com/articles/which-jee-main-score-will-nta-use-for-common-rank-list/amp

All the best.