You can increase the device-session TTL in your loraserver.toml configuration:
# Device session expiration.
#
# The TTL value defines the time after which a device-session expires
# after no activity. Valid units are 'ms', 's', 'm', 'h'. Note that these
# values can be combined, e.g. '24h30m15s'.
device_session_ttl="744h0m0s"