But the date for registration has ended. I tried to call them but none of them answered the call. Then I mailed them on their official mail address and their reply was :Dear Candidate,  Those candidates who have already appeared in JEE(Main) Jan.-2019 Examination, are requested to fill the Application form for JEE(Main) April-2019 with the same application number(JEE(Main) Jan-2019) and password created at the time of form filling for JEE(Main) Jan-2019 Examination, However if the already registered candidate has filled a new application form for JEE(Main) April 2019,their new application form will be rejected and the details filled in the JEE(Main) Jan-2019 will be retained for JEE(Main) April-2019.Such Candidates will apply the online Application Form for JEE(Main) April-2019 with old Application number of JEE(Main) Jan-2019 and password. The Application Fee paid for JEE(Main) April 2019 will not be refunded at any circumstancesPlease sort out this problem. 

  They have that the Application number and password will be retained.So try logging in with the same credentials and check whether they have mentioned any thing about JEE Mains April-2019.I think by  this time admit card is also released check out this and i will be waiting for your reply.