Ideally, by this point, you want your main deck of Astels to be 3-Star, and have a few pieces of Heroic gear that are enchanted. Continue to work your way through main quests, side quests, and Aimee's repeatables.
You will be able to purchase stronger MP, HP, and Astel HP potions from the General or Misc. Vendor, and if your cooking is over level 41, you can craft stronger food as well.
At level 45, you will unlock four new dungeons:
- Fortenora Underground Prison
- Archduke Caleonid Mansion
- Dogavi Black Market
- Dogavi Black Market Expert