Is there a way to update Blender without deleting it and downloading the new version? I like to stay up with the latest version of Blender. I use Blender on my Macbook Pro and it is kind of a pain to update Blender because you have to delete it and then re-download it. 

This isn't a huge deal but is there a way that you can just update Blender without deleting it and re-downloading it every time? It is kind of ridiculous to just re-download the entire program when the new version consists solely of bug patches.
Blender doesn't have an (auto-)update function that would do this for you.

Some years ago I experimented with a way to create binary patches - that works pretty ok, but the experiment never took further form, as an entire infrastructure to support this needs to be created, and for such an effort no resources have been found (people willing to work on it, maintain it and the servers).

Until that day you'll just have to download the entire program. Note that you don't have to install Blender, you can just run it from the location you downloaded and extracted it to (at least on Linux and Windows, so assuming it works also on OS X).