Edit /cache_builders/post_island.php
CHANGE:
$one_month = $html->get_date() - (86400 * 30);
TO:
$one_month = $html->get_date() - (86400 * 60);
for looking back to 60 days.
OR:
$one_month = $html->get_date() - (86400 * 90);
for looking back to 90 days.