hello tarun !!
i am afraid that you might not have any chance to increase the marks in ts eamcet 2021 and there wont be any improvement exam. but there might be key changes so you might have some marks increased if at all any objections or key changes are there.

lets hope for the best

for more details please see :

https://engineering.careers360.com/articles/ts-eamcet

thank you

all the best