systemd : changing locale without rebooting

On a Debian Stretch system, when reconfiguring locales (dpkg-reconfigure locales as well as using localectl) systemd keeps running with the boot setting. Therefore services launched with systemctl keep on using the old (boot time) locale. I tried systemctl daemon-reload and daemon-reexec as well. Nothing does. Is there any alternative to either rebooting or modifying the unit files?