Dear Neha,
CLAT 2018 site displays message that "Admit Card Download is over". In our article CLAT Admit Card 2018 Careers360 suggested candidates to keep extra copies of CLAT 2018 admit card so that in case of misplacement of one, the other copies could be used later. So, officially you won't be able to download it again. but try to remembere if you have saved a copy of that in your hard drive, pen drive or on mobile or you might have sent a copy of it from your mail to someone else. in such scenario you can fetch this from there.
Best of luck!