Make rank reset available in 3 ways:
- Cash shop for $10
- In game currency for $500,000 silver
- Every time the player rank up, give one for free.
Edit: Can also make reset cost scaled to the rank the player is at when resetting. example:
Reset at rank 2 = 10,000 silver
rank 3 = 100,000 silver
rank 4 = 300,000 silver
etc.

, because we all love grinding materials.