Astral Projection creates an astral copy of your body, replicating your possessions.
Your astral body resembles your mortal form in almost every way, replicating your game statistics and possessions. (…) Your astral form can freely travel through the Astral Plane and can pass through portals there leading to any other plane. If you enter a new plane or return to the plane you were on when casting this spell, your body and possessions are transported along the silver cord, allowing you to re-enter your body as you enter the new plane.
The replicates you created with Astral Projection are ephemeral, as discussed here. I think this also means that you can use consumable items or items with charges on the astral plane, without them being actually consumed or used up (the original ones are still on your body).
This will not help you with consumables that enhance your body, like reading a Tome of Understanding or drinking a Potion of Longevity — these will enhance the or rejuvenate the ephemeral Astral Form, but leave your real body unchanged.
However, this appears quiet exploitable with consumable items that do not need to affect your original body. For example, imagine you had a Ring of Three Wishes — you would be able to cast three free wishes a day without ever using up the ring.
Also, you could essentially cast any spell in the game for free, assuming you have a Spell Scroll of it. This in effect would allow you to cast as many additional spells without consuming slots every day as you have scrolls. Of course would have to cast them on the astral plane, so it's probably no benefit for combat spells and such, but something like wish would work just fine. (I think for even more shenaningans, a scroll of Demiplane will be handy — transport all kinds of things and materials that you want to enhance with your spells right to you while you are at it).
Can you use Astral Projection in this way?
Best Answer
Ask your DM.
The spell description simply does not tell us the relationship between the "replicate" possessions held by your astral body and your actual possessions held by your actual body. There is just as much evidence for ruling that your real consumables are consumed when your replicate consumables are as there is for ruling the opposite; that is, there is no indication given either way.
But I can give you one of my "DM pro tips" inspired by the classic "Wish for more wishes" trope (TV Tropes warning): if a ruling results in unlimited wishes, the ruling is dubious. Not necessarily wrong, just dubious. D&D Adventurer's League organized play even has a specific Obvious Rule Patch (TV Tropes warning) of a well known RAW exploit related to unlimited wishes: