Sugar Reform Act of 2013 - Amends the Federal Agriculture Improvement and Reform Act of 1996 to make loans available to processors of domestically grown sugarcane (18 cents per pound) and sugar beet processors through FY2017.

Amends the Agricultural Adjustment Act of 1938 to direct the Secretary of Agriculture (USDA) to make specified sugarcane and sugar beet quantity estimates through crop year 2017.

Requires that sugar allotments be appropriate to maintain adequate supplies at reasonable prices, taking into account all domestic supply sources, including imports.

Authorizes the Secretary to suspend or modify marketing allotments, taking into account: (1) the interests of consumers, food industry workers, businesses, and agricultural producers; and (2) the competitiveness of domestically produced and imported foods containing sugar.

Revises sugar tariff-rate quota adjustment provisions to direct the Secretary to: (1) adjust tariff-rates to provide adequate domestic sugar supplies at reasonable prices, (2) establish and adjust tariff-rate quotas so that the ratio of sugar stocks to total sugar use at the end of the quota year will be approximately 15.5%, and (3) promulgate regulations that permit any country that has been allocated a quota share to temporarily transfer all or part of the share to any other country that has also been allocated a quota share.

Extends flexible marketing sugar allotment authority through crop year 2017.

Amends the Farm Security and Rural Investment Act of 2002 to repeal the feedstock flexibility program for bioenergy producers.