Any school employe who has been granted a leave of absence, approved by the board of school directors, for professional study shall be considered to be in regular full-time daily attendance in the position from which the leave was granted during the period of said leave for the purpose of determining the employes length of service and right to make contributions as a member of the School Employes' Retirement Fund and continue his or her membership therein: Provided, That if the employe does not return to the employment of the school district for a period of at least one year the contributions made by and on behalf of the employe during the period of the leave of absence shall be refunded.
24 P.S. § 5-522.1