40 ILCS 5/6-159
A fireman who receives a refund, and who subsequently re-enters the service, shall not thereafter receive, nor shall his widow or parent or parents receive, any annuity, benefit or pension under this Article unless he or his widow, or parent or parents, repays the refund within 2 years after the date of re-entry into service or by January 1, 2011 , whichever is later, with interest at the actuarially assumed rate , compounded annually, from the date the refund was received to the date such amount is repaid. The change made in this Section by this amendatory Act of 1995 applies without regard to whether the fireman was in service on or after the effective date of this amendatory Act of 1995.
A fireman who has failed to repay any refund due to the Fund under this Article after re-entering service shall be treated as a new employee and shall only receive service credit from the date that he has re-entered service as a new employee.
40 ILCS 5/6-159