Compilations can be re-generated on the Edit Compilation screen where they are created, and they can also be re-generated on the Code List.
Note that the Compilation must first be attached to the Code.
Navigate to Project Menu > Cards > Code List, and click Re-generate icon that appears under the Tools column.
If there is more than one Card created for the Compilation (i.e. Tag Level was selected), once clicked on Re-generate a new pop will appear where can be selected only the Cards that need to re-generated at that moment.
If you do not have the ability to regenerate the compilation you should confirm the compilation has not been changed to manually generated (upon return of compilation). See our article here for more details.