Duky dilmema
Your quilt is so cute....If you embroidered the duck, make another one. See if you can remove the torn one....by the way, I would not use the same applique fabric you used in the first duck. It doesn't look like you can put a hat on the duck....there seems to be some fraying on the front of the duck as well. If it is the fabric falling apart, a hat won't keep it from doing it elsewhere on the duck, when the next person washes the quilt.
Make a new square and had applique the square to the quilt. Then sew a 1/4 inch top stitch all the way around the edge of the block and all the other blocks to quilt it down to the quilt.
Hope this helps
Diana