see http://tex.stackexchange.com/questions/55437/how-do-i-update-my-tex-distribution
Basically, just do
sudo /usr/local/texlive/2014/bin/i386-linux/tlmgr update --self sudo /usr/local/texlive/2014/bin/i386-linux/tlmgr update --all
For TL 2015
sudo /usr/local/texlive/2015/bin/x86_64-linux/tlmgr update --self sudo /usr/local/texlive/2015/bin/x86_64-linux/tlmgr update --all