Moles are just collections of pigmented cells called melanocytes living inside of the skin. As such, they are a normal part of the skin, and you don't have to do any thing special about the fact that a mole was damaged along with other parts of your skin when you scraped your arm.
You will want to keep the area of the scrape clean and dry as it heals. I would suggest that you apply a small amount of an antibacterial ointment to prevent infections. Avoid picking or manipulating any scabs that form, as that may lead to scarring or prevent optimal healing. If you see any evidence of spreading redness, warmth, or pus these may be signs of a starting infection, and you should see your primary care doctor
When you have totally healed up, the mole may come back. This will depend on how deep the scrape was and whether it removed all of the melanocytes that formed the mole. I suspect that, unless the scrape was very deep, that most of the melanocytes are still there and that the mole will come back just as before.
Please talk to your primary care doctor for more information about how this could affect you.