The revolving fund established pursuant to part VII of Veterans Regulation Numbered 1(a) is continued in effect, and may be used by the Secretary, under regulations prescribed by the Secretary, for making advances, not in excess of twice the amount of the full-time institutional monthly subsistence allowance for a veteran with no dependents (as provided in section 3108(b) of this title) to veterans pursuing rehabilitation programs under this chapter. Such advances, and advances from such fund made before the effective date of the Veterans’ Rehabilitation and Education Amendments of 1980, shall bear no interest and shall be repaid in such installments, as may be determined by the Secretary, by proper deductions from future payments of compensation, pension, subsistence allowance, educational assistance allowance, or retirement pay.