First thing to note is that when upgrading your charm you do NOT receive reaping points.... Reaping points can only be obtained by deleveling for the purpose of AA points only!
You will be unable to purchase Necklace of the Reaper Rk 1 after releveling to level 70.
To begin the process locate Reaper in The Plane of Knowledge or Nexus and hail him. He will ask if you would like to earn some additional AA points, you will need to follow this prompt. At the end of the prompt, he will ask if you are ready to de-level. You will lose all levels and no longer have access to most gear stats unless you have pre-farmed for them. You WILL have access to your item clickys i.e. Dmg shield from cloak, so make sure to use them to your advantage. **Note** This is the ONLY way to achieve reaper points currently.
Completing this process 200x will reward Necklace of the Reaper Rk 200
Good luck! Any questions feel free to ask in game or on discord.