Subject to the restriction of Section 35 of the State Finance Act, no grant funds may be made available for expenditure by a grantee for a period longer than 2 years, except where such grant funds are disbursed in reimbursement of costs previously incurred by the grantee and except as otherwise provided in subsection (d) of Section 5-200 of the School Construction Law and in subsection (b) of Section 80-45 of the Department of Human Services Act. Any grant funds not expended or legally obligated by the end of the grant agreement, or during the time limitation to grant fund expenditures set forth in this Section, must be returned to the grantor agency within 45 days, if the funds are not already on deposit with the grantor agency or the State Treasurer. Such returned funds shall be deposited into the fund from which the original grant disbursement to the grantee was made.