systemd does not reload updated Application code

recently I faced this weird problem with systemd, I have a nodejs app and I run using systemd, well everything works, until I do make any changes to my application code and restart my systemd service, But my newly made changes doesn't reflect in execution(unless I restart my machine).

The other thing I observed, if I use very small application test code then it works as intended, I my assumption is my application code size might be causing this behavior.

Thanks in advance.

[Unit]
Description=sandbox
Documentation=https://example.com
PartOf=appbase.target

[Service]
ExecStart=/home/user/.nvm/versions/node/vx.x.x/bin/node /home/user/repo/Server/SandboxServer.js
Restart=always
Slice=limits.slice
RestartSec=10                       # Restart service after 10 seconds if node service crashes
StandardOutput=syslog               # Output to syslog
StandardError=syslog                # Output to syslog
SyslogIdentifier=sandbox

[Install]
WantedBy=multi-user.target

via sumanta