You keep your levels, but individual shard specialties reset.
I TRed Agg after making 9 holy burst shards. When I TRed I had a 100% chance to make them (after 9 times the the 5% increased chance at success after you make each one)
Now, looking at the recipe as a level 67 divine crafter (holy burst is level 72), I have only a 75% chance to craft a shard, and the xp is back up to 96. I'm unsure what it was when I TRed, but am certain it was not still around the 100xp mark.
Just an FYI. Do with this as you see fit.