Hello,

JEE Main 2019 exam will be conducted by NTA and canddates will be allowed two attempts in a year. The exam will be held in January and April. Earlier, each candidate was given three attempts in three consecutive years. There is no changes in the eligibility criteria so the total number of attempts will be six. 
You can refer to the link below for details-

https://engineering.careers360.com/articles/nta-jee-main

Hope this helps.
Good Luck! 

You can go for  3 successive attempts incluidng the year you appear in 12th.

Maximum 3 attempts are permitted in all categories. 

From 2019, NTA shall conduct 2times a year.