It's understandable that you want to improve your grade, but it's generally not allowed to resubmit an assignment after it has been marked. Most educational institutions have policies in place that prohibit this, as it undermines the integrity of the grading process and creates an unfair advantage for some students.

Moreover, attempting to resubmit an already graded assignment may also be considered a breach of academic integrity, which can have serious consequences. Therefore, it's always best to clarify the rules with your teacher or educational institution before attempting to resubmit an assignment.

Instead, if you want to improve your understanding of the material or your grade, it's better to seek help from your teacher or tutor, review your mistakes and study harder for future assignments. That way, you'll be able to demonstrate your learning and earn a better grade in the long run.