Withdrawing and resubmitting applications

There is a position I'm very interested in applying for at HHSC. I think I would be a very good fit. The position was previously posted a few months ago. I submitted an application but didn't hear back. When I reviewed my application after submitting, I realized I could have done a better job explaining my qualifications. I recently saw the position was posted again so I polished up my application to resubmit. However, the Career Center says that I've already submitted an application. Would it be a good idea to withdraw the old application in order to submit the new one? Would that even be possible? (Note: I am currently an HHSC employee)