Use brains and geography: Gnv is in the Swiss-so its reckoned to be an INTerntional trip and these cost indeed sometimes that much=in fact more as the lowest advance ticket (which you wont be able to get in summer/hi-season). Same applies f.e. for direct TGV from Basel to the FRance.

If you want to lower it: take a local train before and change into TGV at 1st FR stop-then maybe with luck its the 10€ in quota or 20 without (which app cannot handle-if you get this message, try other means). Most TGV have 1st stop in FR at Bellegarde-not all.

If you give your travel details (departure date, time and route) here you will get advice on how to make the reservation. There are several ways to make reservations. 

thank you. I have managed to make reservation. The group I am travelling in is rather large. So when I split the group and make 2 bookings for us, it works perfectly.

And yes I cannot avoid the reservation costs because of the international fees

ofcourse you could avoid this expensive Reservation
By useing a regionaltrain till the first french stop of the TGV (just 30minutes after Geneva and board the same TGV from there to Paris You may lost 20minutes time but you would just pay 10€ (limited) or 20€ (until the TGV is full ) for the reservations per person.

Because of that as asked by @AnnaB  Your Route and time is the best help for us to provide you with the best solution.

Here a post about saving on reservation in the France - Switerland section you find the example from the picture.