could try send HR or if u have interviewer's email an email to ask how u can improve? but chances of them replying isnt high since they dont even send rejection email.

maybe meantime try get some work experience and then apply again next year, and i guess think abt how to ans the interview questions since u already know what they will ask... my first interview for a patent attorney position i failed too, I thought I did well then, but maybe i didnt answer the questions as well as i would like to.. but i already know what kind of questions they will ask and what they are looking for, so 2nd time round, got the job

other than this, not sure what else u can do..