To get better flight times I think Lithium Polymer batteries are the way to go. My electrics now stay in the air for around 25 minutes now.
Some of your gear may be able to be switched. The thing about electric is that everything is as light as it can possibly be. If your first glow plane was very small you might be able to swap out your gear. Your rx would be able to move over to gas (as long as it's range was good). Your servos may be too small to go into a glow plane but they work great as throttle servos. Your radio would also make the jump as long as it is FM. The charges I use for my electric stuff comes in really handy for my glow stuff. If I forget to charge a plane or even a tx I can use my field charger and be in business. Hope some of this helps.