5 ILCS 260/11
If a new bond is given by any officer, as provided in the foregoing Sections of this Act, then the former sureties shall be entirely released and discharged from all liabilities incurred by such officer in consequence of business which is discovered from and after the time of the approval of the new bond, and the sureties to the new bond are hereby declared to be liable for all the official delinquencies of the officer, whether of omission or commission, which may occur after the approval of the new bond as above stated; but the provisions of this Act shall not be so construed as to operate as a release of the sureties of any of the above stated officers, for liabilities incurred previous to the filing of a new bond, as required in the foregoing Sections of this Act.
5 ILCS 260/11