Only added a respawn listening event

In the MainClass:

public GokiStats() {
instance = this;
IEventBus eventBus = FMLJavaModLoadingContext.get().getModEventBus();
eventBus.addListener(this::construct);
GokiPacketHandler.registerMessages();

    MinecraftForge.EVENT_BUS.addListener(this::onPlayerRespawn); //Add this
}

//add this
private void onPlayerRespawn(PlayerEvent.Clone event) {
if (event.isWasDeath() && event.getOriginal() instanceof ServerPlayerEntity) {
ServerPlayerEntity originalPlayer = (ServerPlayerEntity) event.getOriginal();
ServerPlayerEntity newPlayer = (ServerPlayerEntity) event.getPlayer();

        StatBase stat = StatBase.stats.get(21);
        final int level = DataHelper.getPlayerStatLevel(originalPlayer, stat);
        if (stat.isEnabled()) {
            newPlayer.getAttribute(Attributes.MAX_HEALTH)
                    .setBaseValue(20 + stat.getBonus(level));
        }
    }
}