O.K. I misunderstood your situation. As muguy's post says, you will need to make new edits on the new HD source files. You may need to start from scratch.
However, you might be able to carry over some of your edits. The basic scheme would be to create a new project and import one of the high def clips into it as the first clip added to the project. That will set the project as a high def project. Then go back to your original project and Edit/Copy the corresponding edited low res clip. Next, Edit/Paste the edited low res clip into the newly created project. Your edits will carry over. In the new project, do an Edit/Copy on the edited low res clip, and then select the unedited high res clip and do Edit/Paste Adjustments. A side menu will appear that will give you some options to select as to which adjustments (edits) can be carried over. Click on one and that should paste the adjustment into the high res clip. Then you can delete the previously edited low res clip.
A time saver may be first to paste all of the high res clips into a new project, and then Edit/Paste, Edit/Copy as a batch all of the previously edited clips from the original project timeline into the newly created project. All edits will carry over. Then you can work with the Paste/Adjustments procedure having all of the clips in front of you. Do a Paste/Adjust on each clip one at a time. After you finish, you can delete the previously edited low res clips. That should leave you with high res clips in your time line with most of the edits carried over from the low res clips.
Possibly not all edits will be able to be pasted into the high res clips, but some may work. You will need to experiment and see.
Sounds complicated, but actually should be pretty easy to do after your first try. If you find it not to be feasible, then your only option would be to manually edit the high res clips.
-- Rich