9 FAM 42.74 N1 ISSUING REPLACEMENT VISA DURING VALIDITY OF ORIGINAL VISA (CT:VISA-2270; 03-31-2015)
a. If you are satisfied that an applicant will be or was unable to use an immigrant visa (IV) during its validity period because of reasons beyond the applicant’s control and for which the applicant is not responsible then you may issue a replacement visa with the originally allocated visa number within the same fiscal year even though the visa has not yet expired.
b. You should recall and cancel the originally-issued visa and collect once again the appropriate IV application processing fee (including the Diversity Visa Lottery Fee for a DV applicant), unless the applicant was unable to use the visa as a result of action by the U.S. Government over which the alien had no control and for which the alien was not responsible.
c. An applicant who will be or was unable to use an IV during its validity period because of reasons within the applicant's control can submit a new visa application if the petition has not been revoked and if the basis for immigration still exists (i.e., familial relationship).
This also applies for new IV applications outside of the original IV's fiscal year of issuance.
9 FAM 42.74 N1:
http://www.state.gov/documents/organization/87915.pdf