The LEEDv4 for Homes Reference Guide is not explicit on whether a previously developed property is eligible for the Infill Development points. On the one hand, the suggested maximum point total (8 points) seems to suggest that it would not, since using Previously Developed (4 points) + Infill (2 points) + Open Space (1 point) + Street Network (1 point) + Bicycle Network (1 point) = 9 points.
But, on the other hand, a Previously Developed site could be surrounded by ag land. It seems like there's more environmental benefit for a Previously Developed site in the middle of town, so it should be eligible for Infill points as well. Furthermore, why should an infill greenfield site receive more points than a previously developed site that is also infill?