from The American Heritage® Dictionary of the English Language, 4th Edition
- intransitive v. Informal To enlist again for military service.
- intransitive v. Informal To sign a renewed contract for employment or service.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- v. To reenlist; to renegotiate a contract
- v. To refill one's drug stash
Possibly blend of re-enlist and sign up (Wiktionary)