As you read in the title above; to update your Python packages via pip.
for Linux/*nix:
pip freeze --local | grep -v '^\-e' | cut -d = -f 1 | xargs -n1 pip install -U
p/s: you may need to run as sudo. Probably.
for Windows:
for /F "delims===" %i in ('pip freeze -l') do pip install -U %i
Credit:
http://stackoverflow.com/questions/2720014/upgrading-all-packages-with-pip