I've been using the pre-made full installers for so long that I haven't checked the process of updating from 1.0-1.4.
The
1.5.0 page has an all-in-one package for 1.5.0 and instructions for getting things started from a retail install. It's a bit involved but you only have to do it once.
The
1.5.1 page links to files for updating from 1.5.0 to 1.5.1 including the 1.5.1 asset pack, optional 16-bit HQ texture pack, and optional Ogg Vorbis music pack. I need to make an all-in-one package since these aren't going to change much. You'll probably want 1.5.1.17 (not 1.5.1.18) for online multiplayer since that's what players on the battlezone1.net Anet server are currently using.
Finally, the
1.5.2 page has links for updating 1.5.1 to 1.5.2 including the 1.5.2 asset pack. This is a bit of a moving target but an all-in-one package could include at least the stable content. You'll want the latest 1.5.2.x build if you want to play the new Lua-based Instant Action or Multiplayer Instant action maps.
You may want to keep separate installs of 1.5.1.x and 1.5.2.x.
