Hello,

Yes, the sole reason to conduct improvement exam is to give students a second chance to improve their marks and perform better if they couldn't perform well in regular exams. If you got less marks in a subjects in improvements then the marks scored in regular exams will be considered in that subject for getting admission in higher studies.

Hii!
See, when we talk about the improvement exam, and the individual Subject, the best out of the two scores will be taken into consideration if you fail to obtain better marks in the second attempt.
As a whole, your percentage of marks will improve if you do better in other Subjects and get more marks than earlier. But,this may differ. For example, you will not be considered pass if you failed an exam with low marks and score even low, in second attempt, apart from you getting an over-all good percentage in the second attempt.
Hope you understand.
Good luck!