We believed so, but we asked Ofgem, just to be sure.

They confirmed:

The FITs Order does not discuss the building of new generating stations on the site of a previous station. Part 4 of the Order does however discuss extensions to accreditations. Assuming that the installation is completely new and not an extension to the previous generating station and that it does not utilise any residual apparatus from the previous generating station, it is unlikely that positioning a station on the site of a previous generating station would affect the eligibility of the station for FITs or that previous RO accreditation would have an impact.