A patient loses the PDF in March and asks you to send it again. Between then and now you changed a price, and you edited the visit. What you need is the document you sent, not a new one.
What gets saved
Every time you choose Generate & download PDF on a visit's Superbill page, Goji saves a record of that export before the file reaches you. If the record cannot be saved, the export fails with a message to try again, so a superbill never leaves without a record of what it said.
The record holds the details the PDF was built from, including the procedures and units, the diagnosis codes and the charges and amount paid taken from the invoice. It also holds the choices behind them: the treatment minutes used, the electro-stim setting and the add-on codes you ticked. Each save notes who generated it and when.
Downloading it again
At the bottom of the Superbill page, Previous exports lists that visit's saved exports, newest first, marked Most recent. Each row shows the date, the procedures, the diagnosis codes, the total and who generated it. Download again rebuilds the PDF from the saved content, so a later price change or a different code selection does not alter it. Downloading again is recorded in the access log.
If what is selected on the page would now print differently from the latest export, the section says so, so you know a fresh export would not match the one you sent.
A corrected superbill is a new export added to the list. Earlier ones are never edited or removed. For how the page itself works, see Superbill export.