It is easy to stay current with the most recent LAMMPS patch releases if you use Git or SVN to track LAMMPS development. Instructions for how to stay current are on the Install git and Install svn doc pages.
If you prefer to download a tarball, as described on the Install git doc page, you can stay current by downloading "patch files" when new patch releases are made. A link to a patch file is posted on the bug and feature page of the LAMMPS website, along with a list of changed files and details about what is in the new patch release. This page explains how to apply the patch file to your local LAMMPS directory.
NOTE: You should not apply patch files to a local Git or SVN repo of LAMMPS, only to an unpacked tarball. Use Git and SVN commands to update repo versions of LAMMPS.
Here are the steps to apply a patch file. Note that if your version of LAMMPS is several patch releases behind, you need to apply all the intervening patch files in succession to bring your version of LAMMPS up to date.
patch -bp1 < patch.12Dec16
make purge make package-update
IMPORTANT NOTE: If you wish to edit/change a src file that is from a package, you should edit the version of the file inside the package sub-dir of src, then re-install the package. The version in the src dir is merely a copy and will be wiped out if you type "make package-update".