Does LOL rank reset every season?

Yes, your preseason rank does matter in League of Legends. Even though it gets reset at the start of the next season, you can still set yourself up for success (or failure) during preseason play. If your preseason rank is high, you will have a higher rank potential when you play your placements.

How often does ranked reset?

While Rank may have changed, the Reset period – which always happens on the 13th of each month – has not changed. Instead of Rank Reset, it is now Grade Reset and unlike Rank, will take players back to the lowest Grade each time.