Well, starting what? Starting the node’s sketch from start? That’s what many would call a reset.
If your node is going into some deep sleep during which it loses its program state (memory contents) and after which it starts from scratch again, then it should somehow save the secrets, RX settings and frequencies it got through OTAA (or changes it got through ADR), and keep the last value of the uplink and downlink frame counters. LMiC does not provide anything to do that, but supports setting the known values after a reset, if you somehow saved them.