Related Clues:

• Begin a second hitch
• Enroll for another year of duty
• Continue one's military service
• Go back for more
• Extend a membership, say
• Agree to another stint
• Extend, as an employment contract
• Go for a second tour
• Agree to a second stint
• Volunteer for more
• Extend one's tour of duty
• Take another tour
• Opt in again
• Sign on for more