The bad news: unfortunately you can't get your exact save back. Data is stored in localstorage and it's possible to be deleted especially on browser history clear or if there are privacy extensions :(
The somewhat good news: saves are in plaintext, and you should be able to edit them and get back some progress. In this case I'd recommend exporting the save, editing "playerBankedXp" to something high (maybe give yourself a couple more levels for the trouble? lol), and blaze through early game. For item drops, if you spec for drop rate, you should be able to reach 100% drop rate for most items. And for archives, I won't spoil too much, but there is a stage that gives you ridiculous amounts of int
Apologies for your data loss, I hope this helps!