It’s possible to refresh assets such as MOV and TIF files, but not an AEC, since the AEC doesn’t reside in the Project window as an AEC file. In other words, there’s no AEC file to click on and refresh — just comps.
If you change your C4D animation, you have to make a new AEC file and TIF (or whatever) files from C4D. You’d then have to import the new AEC file (and TIFs) into AE, which would give you new comps. You can then copy the null/camera layers from the new comps and paste into the old comps if you want, or work in the new comps.
Sometimes when you import something into AE, no link is maintained. It’s the same way when importing AEP files. There’s no link there.
Hope that helps.