If you didn’t use cloud save, the save game is stored in your browser.

In my experience, the most common way for my save to vanish was that I used the wrong game URL. If you use http instead of https or vice-versa, or you load the beta, it’s a plain canvas. The save is unique to the location.

Hopefully it helps. Otherwise, don’t worry about “cheating” yourself back to roughly where you were. Don’t grind if you don’t enjoy it :)

I recently went into IW space myself, and wondered about the same thing. Clearly, you could try to aim for 40K years, for the “fun” of it.

I decided to just reset and play regular. There are other fun challenges.

Also, I also used to play IW exactly like you describe, from a fresh game. It never really occurred to me that I could also just IW in my veteran save with 250K paragon + faith bonus. Only took a few days to explore the galaxy with that.