Here are the steps for the "change monorail direction" from the beta forum that will also help with any situation where you build an entire circuit and somehow got the station going the wrong way.
1. In the first picture, there is a completed circuit with the monorail running counter-clockwise:
2. Destroy the station and use auto-complete to build a stationless complete circuit:
3. In this example, we want the station to run clockwise instead, so we next destroy enough track to give some room to build the new station but not yet connect to the rest of the track:
4. After building the station, use auto-complete and enjoy. The trains now run clockwise:
Original credit goes to Jcontardo who described this in words in a bug post. This is an illustration of the workaround that has worked for me every time for coasters, monorails, whatever.