I don't know. This is what I found in the BOL for Change Tracking:

"Maintains a list of all changes to the indexed data. Changes made with WRITETEXT and UPDATETEXT are not detected. You can update the full-text index with these changes immediately, on a schedule, or as they occur, using the background update index option."

I found this under the topic of Full-Text Indexing Support:

"Change tracking population
Maintains a record of the rows that have been modified in a system table, and propagates the changes to the full-text index. You start the change tracking by executing sp_fulltext_table and specify start_change_tracking for the @action parameter. When using change tracking, you also specify when the changes are taken from the history table and populated in the full-text index:

Background
After starting change tracking with start_change_tracking, you can execute sp_fulltext_table specifying start_background_updateindex for the @action parameter. With this option, changes to rows in the table are propagated to the full-text index as they occur.

On demand
In this option, all tracked changes are stored in the history, and only propagated to the full-text index when you execute sp_fulltext_table specifying update_index for the @action parameter.

Scheduled
You can use SQL Agent to schedule periodic jobs that execute sp_fulltext_table specifying update_index for the @action parameter. This will propagate all outstanding tracked changes to the index.
"

I looks like sp_fulltext_table is a good place to start.

-Mike