I think the default /etc/init.d script for uwsgi-python allows specifying the "app" name (actually it's the name of the config file) only for "status", i.e. /etc/init.d/uwsgi-python status appname
However, pids are in /var/run/uwsgi-python/appname/pid. If I'm not wrong, sighup to the master process reloads, so kill -1 `cat /var/run/uwsgi-python/appname/pid` should do the job. Consider also using the "touch-reload" option of uwsgi