The purpose of this study is to determine if an additional intravenous (IV) dose of Ustekinumab is safe and effective in helping Crohn's disease patients, whose initial response to Ustekinumab was followed by loss of response to Ustekinumab, to regain response to Ustekinumab for the treatment of their disease.

This study is designed to last 10 months. Eligible participants will have 2 screening visits, 3 drug administration visits, and 2 follow-up visits.

Participants have a 50% chance of being randomized (like drawing names out of a hat) into either the Ustekinumab re-induction group or the continuous maintenance group. Participants in the Ustekinumab re-induction group will receive intravenous Ustekinumab at the baseline visit. Participants in the continuous maintenance group will receive subcutaneous Ustekinumab at the baseline visit. All participants will receive subcutaneous Ustekinumab 90 mg for subsequent visits.