You stated;
delete some logs in my /var/log directory
But you neglected to tell everyone which log files your talking about. If they are not system logs then you need to setup log rotation for any log file outside the scope of what is currently being rotated by the system.
If log rotation is for system logs (default) and they are not rotating like they should then you need to find out whats going on with your log rotation.
If these are log files, not part of the system logs, then you need to setup your own logrotation as part of the systems.