First, try running the refind-mkdefault script that comes with rEFInd. If you installed rEFInd via a Debian package, typing sudo refind-mkdefault in a Terminal window should do the trick. If you installed in some other way, you'll need to find the script. (I comes in the rEFInd .zip file, for instance.)
Second, if that doesn't work, then you've probably got a buggy UEFI that's forgetting its boot order. I Googled your computer's name, and found reviews of it from 2012, and UEFIs from that era were notoriously buggy. You may want to read this page of the rEFInd documentation to learn about how to deal with such problems. In particular, the last section, on using the fbx64.efi program (renamed as EFI\BOOT\bootx64.efi on the ESP), may help work around the problem. In brief, you may need to rely on the UEFI's fallback boot loader (EFI\BOOT\bootx64.efi), which is run when other boot loaders can't be found or are invalid. This may require you to rename any other boot loaders that are currently running, though. Unfortunately, it's hard to provide precise instructions that are guaranteed to work, since there's so much variability in how those old UEFIs are broken, as well as your own software/OS installations.
