What I've done to limit the number of repeats entered is to include a note after the repeat that shows the total repeat count entered and has a constraint to prevent the enumerator from completing or sending a form that doesn't have the desired number of repeats.
https://docs.google.com/spreadsheets/d/1SjG9XBxvYqjg33pre1R8bEyRfqWuKE0jeNypwhbYAnw/edit#gid=0 shows an example.
Notice that I gave the note question a default value. This is because constraints are not evaluated on questions that don't have a value. Setting a default forces evaluation. You could include the second line of your message there so there isn't a weird 0.