Simple answer is no.
Complex answer that I can explain but I don’t have an example or code for. You could add custom JavaScript to the admin that detect when the header row of the repeater field hits the top of the screen and then fixes the position at the top of the screen. You’d also need to detect when to unfix the position of the field. Like I said, knowing what to do and doing it are two different things.
Unless you’ve already done the display of this repeater field you might try a different solution. For example instead of a table with one field for each day you could have a single checkbox field with each day as a choice. Then you’d see all the days listed for each name. You could also mess with the width of each subfield and the display properties to display the day chechboxes next to the names.
