Nothing special is required.
What it *should* do is to look at the date of the last database entry when the driver starts up. It also looks at the data available on the HP1000 console and checks to see if there is data there that is AFTER the last database entry date - if so it should request that before going on to read the 'current' data.
There might be a bug in the section of code that is executed when the database is empty (I must admit that I tested this once only when I was getting this started). To make sure that the 'history' records are being read, I suggest that you stop the weewx code for a little while and then start it up again while looking at the system log. You should see messages that it is reading the history and then later that it is reading the current data. If it is doing this correctly, then it means there is a bug in the 'unpopulated database' section of my code.
If it is still not reading the historical data then I'll need to see the logs and try to dig a bit deeper.
(Minor point: is the Froggit HP100SE console exactly the same as the Fine Offset HP1000? I'm clutching at straws here...)
Susan