AMCAS 2012 Vs AMCAS 2010

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i think you need to re-enter everything once again. so you will have to update your LORs and also your transcripts.
 
My 2008 coursework was preserved in 10 and 11.

I suggest opening an app for the current year, for continuity. Don't submit.
 
You do need to resend transcripts and LORs. I do not believe you will have to retype the old classes into the system again.