TV Land has picked up its most successful original series, “High School Reunion,” for a third season.Mike Fleiss-produced reality series is averaging 883,000 total viewers in its ongoing second campaign. In the MTV Networks channel’s target demo of women 25-54, it’s averaging 554,000 viewers. Series is produced by Fleiss’ Next Entertainment in association with Warner Horizon. Meanwhile, also announcing series renewals, Discovery’s Planet Green channel has reupped five of its frosh skeins, with “Emeril Green,” “Focus Earth With Bob Woodruff,” “Greensburg,” “Renovation Nation” and “Wasted” returning for second seasons. The season openers for these series will highlight an Earth Day-themed week for the cabler starting April 19.