If there are changes in the Constraints / Column name and Table names then the project should be recreated.
If the change is only Schema Name , then you can edit the Plan and make the following changes :
a. For Schema Name change > Edit the Plan > Source Settings :
i. Choose the Table for which the Value should be changed > Select "Override data source setting'
ii. Under Source and Target > Update the Runtime Source Owner name and Target Prefix Name.