Google Indexes TTL

I really would like to know what is the time to live (TTL) of Google indexes. This blog of me changed design and back end in July (OK, end of July). We are in the beginning of February. Being a nice boy, this counts as six months.

And, after six months, I still have lots of lots of missed hits to posts that were published in the old engine and that are, yet, live in Google servers. What I need to do to make Google update their indexes and remove all this crap from there?