http://www.dafyomi.co.il/bkama/insites/bk-dt-068.htm
You ask: what sin did he repeat?
I don't hear the kashya. ShShanu BChet says he repeated sinning. Why are you hung up on finding the exact in that was repeated identically? M'Hecha Teisa? He sinned again. That's all those words mean.
Fred, iowa city us
The writer of this piece understood that Rabeinu Yehonasan and the Meiri were both trying to explain where there is a repetition of the same Cheit. I imagine that from this understanding of the Rishonim he assumed that they understood that there is a repetition of the same thing.
However, I blieve that you are correct in saying that this is not the Pshat. What Rabeinu Yehonasan and the Meiri are in fact coming to explain is how the explanation of Shina b'Cheit fits into the original words of Nishtaresh b'Cheit. Rabeinu Yehonasan says that by repeatedly succuming to his Yetzer he has become more deeply entrenched in Cheit. The Meiri's Pshat is very similar.
Dov Freedman