Bitcoin-qt falls behind on blockchain, how to replace? On Apple Mac, bitcoin-qt is 14 days behind. Never approaches current time. Have downloaded current blockchain from trusted source. Where to install? What procedure?
I know that there is a torrent where you can download the blockchain to jumpstart your fresh installation. This should also help to update your local wallet. In order to download and import the blockchain manually have a look at the instructions and the download link in this bitcointalk thread:

https://bitcointalk.org/index.php?topic=145386.0