I find that running a report to the "Excel Data" or "CSV" output types is not the same as running it to "Excel".
Excel output will include what is on the report pages, including a good approximation of the formatting features, with a tab created for each page. If there are too many rows on a page, an additional tabs are created as needed. The default maximum page length for output to Excel is 65000 rows, but it can be changed.
Excel Data and CSV can produce odd results. In my experience, these output formats return the first query from the first page of the report. For example, if you have a list on the page, but you also are running a small query to produce page header information, you'll get only the output of the query that produces the header info. Plus, it's the query output, not the report output. So if my header shows city and state, but the query also includes country, the output spreadsheet will include city, state, and country -- so, not what's on the page.
So, in your case, you won't get the results of the query that feeds the repeater.
Excel Data and CSV produce results that confuse users. In my opinion, it should not be used. Craft your report to produce exactly the output you need. If that's a simple list like you would use in Excel to feed some other process (so... a Cognos Analytics report as an ETL tool?), your page should contain no header or footer information and only a simple list that looks like what you want.