Job application. Shall I proceed or not.

I have come across the same vacancy that I applied for last year.
I had gotten a interview but failed it. I had no knowledge on what to say and how to behave in an interview then. Since that time I have become more confident in interviews and I am keen in applying but since its the same employer should I apply or will it seem to desperate.
Also if I was to apply should I mention it in my covering letter that I have previously applied.
Thank you

I wouldn't volunteer the information but would answer truthfully if asked. If the job is still open after a year, they may be more desperate than you are if it is in fact, a real job.

If they bring it up, you could stress how you're still strongly interested in being a part of the company's team, and how you are thrilled to have another opportunity to speak to them. Tell them what you have done and learned in the past year that makes you an even stronger candidate for the position and a greater asset to the company.