A partner may re-certify a product at any time, and must re-certify before expiration in order to avoid losing its certified status.
A certification is considered a "recertification" only if that same product has previously been awarded the same Ed-Fi certification and that product can generally be considered to have evolved from the same code base and technology as the previously certified product. For example, a product that was acquired from a third party and substituted in the market for a previously certified product would not be eligible for recertification.
Recertification requirements are described under the applicable certification - consult Available Certifications.