Excise duty exemption repeatability permitted for units undertaking a second substantial expansion when conditions of the current notification are met. An existing unit that availed excise duty exemption earlier by substantial expansion may avail exemption again by a second substantial expansion under the later state-wide notification, provided it satisfies the eligibility criteria and procedural modalities specified in that notification; the earlier and later notifications operated through a refund mechanism, contained no sunset clause or explicit bar on repeat benefits, and administrative guidance is to be issued to field formations and taxpayers.