I need to be able to visualize or at least export 30 days worth of data broken down by the day dimension. Example, unique visitors to page URLs by day within a 30 day period but I am limited to 15 days. Is there a way to extend the limit?
If you are only looking at a single URL (like in your sample), it's actually much easier to add the Day Breakdown as a sub of the URL (rather than across the top with your metric). You won't have the limitation that way.
There are a few "gotchas" with your current layout:
1. The more columns you have, the harder it is to read and to access the settings for each column
2. This one is a big one... if you plan on using this report over and over again, the dates added as columns don't roll! Which means every day you reopen the report, those date are locked to what was originally added.
If you are trying to do multiple URLs, then the report can get really large really quickly... You can break all the URLs down by Day, but then you will get a lot of rows (X URLs multiplied by Y Days, plus the original X rows showing the total for each day per URL)
If you are just planning on exporting the data, then you can always transpose the rows/columns in Excel.
This allows you to make direct API calls from Excel to Adobe and to format the data in Excel like you have here, but without the column restrictions (since spreadsheets lend themselves better to a many column sheet). This will also allow the Dates to roll if you set up a rolling date range.