HELP!!! DILEMMA!!!

So I've been at my job since September 2016 and since about last summer I've made it known to my boss that I would like to move to a new position in the department. I have taken every test for my current position and this other one as well. Just when I was coming back from leave he let someone go and put up a posting for the position I am looking to move up into. I was a bit upset but understood I needed more training and the person hired has 18 years experience... well now I just noticed that a job posting for the job is up online again... how do I approach this?