I would make a COPY of the current project, so as not to make changes to original project. In the new version, create a new sequence at the 4k specs, and then copy/paste contents of the 1080p sequence to the 4k sequence. I don't know of an automated way to do this, but manually, you can right-click clips in the bin and "Make Offline", and select again and choose "Link Media" and point to original RED file.
If original RED clips and the 1080p clips are exact same length, then the edits should be intact. I do something similar quite often and works fine with substituting clips (I will edit a wedding ceremony, then decide I want the whole thing DeNoised - I create a clean clip with After Effects, then plug that into existing edit replacing original and it is seamless, all cuts in sync perfectly).
Note that Premiere titles are going to be at 1080 and may appear smaller in 4k project. Open existing title from timeline, and in titler make new item from current, which should make a copy of the title, but at 4k. The use Replace in timeline to substitute 4k version (right click title in timeline and choose Replace from Bin). I just went through this when moving from a 720p sequence to 1080p.
Hopefully these ideas work in your situation
Safe Harbor Computers
You can try making the sequence offline and relinking to the R3Ds and see if that gives you any luck with automated relinking.
Alternatively, you can export an XML, send it to the Resolve Lite, populate your media pool with the R3D mags, import the XML into the Resolve, relink the QTs to the R3Ds in the Resolve and export an XML and re-import that into Premiere. This is a little similar to the traditional offline/online workflow, except that you're just using the Resolve for re-linking instead of grading.