Omega Race was cool; if you're doing something like that, best of luck man!
As for your question, one way that might work (haven't tried it though) is to change the player's angle on contact with the boundary. If facing right is 0 deg, straight up is 90 and straight down is 270; when they contact the boundary, add or subtract 180 deg based on their current angle. If it's it too radical, modify the numbers to suit how you want it to look. Essentially, you want to reverse the direction of movement right?
Another possibility: Do you have an invisible wall set up at the edges? If not, create a simple line sprite and set it to solid; you can put the opacity at 0 so it's not seen in the game or just set it to invisible at the start. If you have bounce on solids, the behavior should appear when the player contacts this unseen boundary.
Take care, dude.