There are basically four solutions that do not involve extensive work on your bike:
- Roll up the pant-leg on the gear-side high enough to stay away from the gears.
- Wear tight fitting cycling pants that don't flap.
- Use braces as you have, or clips such as these to keep your flappy pants close enough to your legs.
- Stuff the pant-leg on the gear side in your socks.
Since option 3 doesn't work for you that leaves you with options 1, 2 or 4. However, when applying the braces or clips, (or stuffing your pant-leg in your socks) are you taking care to make sure all the excess pant-leg material is collected on the outside of your leg, away from the gears?
On the bicycle side: Chainring guards might help a bit, even better is a full chainguard but these may be hard to find for your bike.