By default, SharePoint 2013 Search shows 5 options for each refiner, except result type, which has 6 options.
In order to change the number of options you need to edit the Filter_Default.html display template. Do to this open Site settings, then Master pages and page layouts. Drill through to Display Templates -> Filters. Download a copy of Filter_Default.html.
Change the values for shortListSize as required and save the file. Upload the file to the document library where you downloaded the copy and overwrite the existing file. Refresh the search page to see the change.