Yes, if you accept any college or nit this year then again you can give jee mains exam if you are in 1st year of the college and once again you can register for jossa counselling. For jee mains you can give atmost 3 attempts but for jee advanced only 2 attempts are there and after that you cannot give jee advanced.
And yes you can again sit in jossa counseling next year, as you will give jee mains again then any student who gives there jee mains can take part in jossa counseling. There is no such criteria that once you have taken part in jossa counseling then you can not sit in next jossa counseling. But if you will not give the jee Mains exam next time then you can not take part in jossa counseling.

For eligibly criteria for jossa counseling you can check the link given below :-
https://engineering.careers360.com/articles/josaa-eligibility-criteria/amp

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