I don't think that's possible as it just grabs your transaction history and makes the graph from it.
Maybe create a new wallet? (if it's not an inconvenient option).
Damn okay. Creating a new wallet seems like a trek, since I'd have to migrate all the coins to the new wallet and write down the recovery info, etc. etc.
I would imagine it wouldn't be a difficult fix for Ledger to carry out, if they wanted to add this feature. Every time the user resets they can simply modify the start date of when the transactions start being counted.
But apparently I'm the only one that has this demand