Train from Lucerne to CDG Airport, Paris

There are two ways:

1. Luzern-Basel (covered by the pass) then TGV Lyria to Paris Gare de Lyon and RER (suburban train) or taxi to CDG Airport
2. Luzern-Basel as above, then Basel-Strasbourg by regional train (TER) and Strasbourg-CDG Airport by one of the direct trains (there are only a few of those per day).

2 is much more convenient, faster, but has fewer daily connections.

Don't. Go to Paris the night before your flight. Always be in the city of a high stakes flight the night before.

other answers in the cross posted thread in the Switzerland Forum

I agree with Janet. Allow for service disruptions on the rail lines.
I would go with Balso's first suggestion via Basel to Gare de Lyon in Paris.

An overnight in the city of Paris is far more enjoyable than an overnight at a hotel at CDG. You can taxi or take the RER B to CDG the following day.