(a) Upon the termination of the period of probation, the probationer shall be released from probation and shall not be liable to sentence for the crime for which probation was allowed; provided, however, the foregoing shall not be construed to prohibit the conviction and sentencing of the probationer for the subsequent commission of the same or a similar offense or for the subsequent continuation of the offense for which he was previously sentenced. The court may at any time cause the probationer to appear before it to be admonished or commended and, when satisfied that its action would be for the best interests of justice and the welfare of society, may discharge the probationer from further supervision.

(b) Upon the request of the chief judge of the court from which said person was sentenced, the case of each person receiving a probated sentence of more than two years shall be reviewed by the probation supervisor responsible for that case after service of two years on probation, and a written report of the probationer's progress shall be submitted to the sentencing court along with the supervisor's recommendation as to early termination. Upon the request of the chief judge of the court from which said person was sentenced, each such case shall be reviewed and a written report submitted annually thereafter, or more often if required, until the termination, expiration, or other disposition of the case.