You have to be in good condition all the time. Sometimes our reserves of Witch power become empty due to worry, stress and battling with enemies. When you have done may spells to defend your interests, that is, you may feel like your fuel tank is empty, it is time to do spells to fetch occult power from our egregore. The Satanic egregore is a large energetic structure and is fed with occult power by multiple sects all over the world. Link to this structure to fill your fuel tank to the brim.
Your power will be restored over one moon cycle. I advice to repeat this particular spell regularly some 5-10 times until you feel that your powers are restored. You will feel when to stop filling your tank with occult power. Should you leave your physical body often during slumber and your experiences feel lucid to you, then you know, it is time to stop filling your tank.
The best time to do this spell is the full moon and the period of 5 days to the full moon night. You will need:
a black candle
some oil to rub the candle with (Marsian oils come to mind: iron in olive oil)
a book about Voodoo, Witchcraft or the Goetia
a photo of a Witch inside the book is good to have (you will place your jewelry on this photo)
your occult jewelry: pentacle, inverted cross or ankh…
the seal of Lucifer
Place the jewelry on the photo of the magickal practitioner and cover with the seal of Lucifer. Close shut the book. Do this 24 hours before you plan your ritual. In this way you are charging your jewelry. When you do your ritual you should consecrate the seal and the jewelry by calling the four Princes of Hell and asking them to grant you more occult power. Use the book during your sorcery as a source of occult power. And so shall it be. Wear the jewelry all the time. The egregore will help you to restore your powers.