Travel between airports in Paris

You need 2 hours just to navigate at CDG. No way would I try to make this connection anything could happen. The airfare will not be cheaper if you miss your flight.

Your question is a bit unclear.

What is the scheduled departure time of your flight from CDG to Newark?

What is the scheduled arrival time of your flight landing at Orly?

If you only have 2 hours between your arrival at Orly and your departure from CDG, you'll never make it. You should be standing at the check-in counter at CDG at least two hours before takeoff....many airlines are recommending 3 hours. It'll probably take you an hour to make the transfer between airports, even with a shuttle, providing you don't run into a traffic jam. And, at around 60 euro for a shuttle, it's not cheap. If you miss that flight home to Newark, you're SOL, with no recourse availaable to you. Come in the night before, enjoy an evening in Paris, then head to the airport the following day.....or find a much earlier flight from Montpellier.
Or you could take the train. Check out tgv-europe.com (keep it set to Great Britain as your home country.) You'll find advance purchase deals as low as 63 Euro per person for a TGV run leaving at 6:51 am and arriving at CDG Terminal 2 at 10:57 am. Check your exact travel dates to see what's available.....90 days in advance, I believe, are available.
Edit: If yo do check tgv-europe.com (the website of the French national rail service where you can puchase tickets) type in "Roissy" as your destination (the town where CDG is actually located.) CDG Terminal 2 will pop up as the destination to select.

Thank you -I'll research the train right now!!