I'm pretty sure this can't be done, but wanted to see if anyone else had any suggestions.
During a migration to a new server, I dumped the repository from our old server and loaded it successfully. Started making commits to the new server, no problems at all. But after a few days, a DNS error started me committing to the old server again.
Now I've realized this problem, I can easily fix it by doing the dump and load process again, but I will lose change history for those few days where I committed to the new server. Is there a way I can merge these two repositories while keeping the change history from both?
can easily fix it by doing the dump and load process again, but I will lose change history for those few days where I committed to the new server
No.
Loading dump into existing repo is additive operation: if you'll dump revision-range from OLD svnadmin dump -r MIN:MAX ... (erroneously committed) and load into NEW only this dump, revisions will be added on top of old history