Ray, if memory serves, I think you have to claim the draw. Once you have got a triple repetition (or double, I should say), look at your control panel and the relevant part should have changed to claim a draw rather than offer a draw.
The reason I know this is I only escaped a very embarrassing defeat by scrambling my way to a draw by repetition. (Insert sheepish-looking emoticon here.)
I TELL YOU I AM THE CHESS MASTA DISASTER
Is there something I have to do to declare a draw?
As has been mentioned, a draw by repetition is optional, not automatic. When the position on the board is one that has also appeared at least twice before (it doesn't matter how many moves back for either previous appearance), then either player may claim a draw. When such an eligible position is present, the button that usually reads "offer draw" changes to read "claim draw". It's very easy to miss if you aren't aware of the draw condition and already looking for the button to change.
Also note that the draw has to be claimed while the board is still in the repeated position. If another move is made and now the position is no longer one that has appeared twice previously, the opportunity to claim the draw has been lost. It might arise again if the same position appears yet again (or a different position shows up for a third time), but it's also possible that for the rest of the game the option to draw by repetition would not occur again.
How is a draw declared by repetition?
I thought at one time it automatically called a draw when same position was repeated 3 times. Now it seems not to?
Is there something I have to do to declare a draw?
Thanks!