Hello there,
You are correct in saying that you will not need to go through another set of PST again after having been to the 1st and 2nrd interview rounds.
With regards to whether you will get an interview when you re-apply after the next 12 months, there is no certainty on this.
Note that the firm will carefully looks at your trajectory within the next 12 months, whether you have met the expected trajectory of a potential candidates that have been progressing in their career for 12-month period since the last time you had the interview.
If you did not display such trajectory, there is a risk that you are deemed underqualify, as I have seen some people experienced.
Hence, it is important to understand that just by having the exact same profile / CV as the current one would be a safe option for you to get an interview, it depends on what will you do (your career trajectory) within the next 12 months. Do pay attention to this alongside with working on your case.
Hope it helps.
Kind regards,
Nathan