As others have noted the Who Do You Think You Are schedule for upcoming episodes has changed. (Link to Ancestry's page which has the full schedule. I was unable to find a schedule on NBC's site.)
April 9th they're re-airing the first episode with Sarah Jessica Parker. Repeats are common, and I don't find this horrible. I'm sure many missed it the first time.
April 16 - they're replacing Who Do You Think You Are with a Wal-Mart produced original movie: Secrets of the Mountain. View trailer below:
Family secrets are uncovered in the movie, and it's clear from the tagline "One family's adventure, every family's challenge" that they're linking the movie thematically to WDYTYA. It can be looked at as trying to garner viewership of the movie from WDYTYA fans - or trying to gain more viewership of the final episodes from those who are likely to tune into the movie. Likely both are intended. Whether the tactic will be successful in either direction is open to question.
Update 4/2: I found an old schedule listed somewhere and realized that April 16th was planned as a week off from the start. The change was a repeat being inserted on April 9th, extending the schedule one week.