Did you check on ebay? They have quite a few pieces in this pattern. I didn't see a tray, but there are some serving platters. You could also have ebay alert you if anyone lists this item.

Hi. Thank you for taking the time to read this and I need help very badly. A serving tray in my house was broken. the label on the back said Mikasa (Manufacturer) Studio Nova (No Idea) Fresh Mint (Pattern) and was made in Italy. I have been searching online for this item for hours and have found almost every single possible piece in the collection except my piece. The tray is 17" x 12" and I have already looked on the replacement site etcetera. I would appreciate it so much if somebody could look up this item from the collection and answer me with the link. It is a white tray with pink, yellow, & blue tulips in the center. I would really appreciate this!