I don't own an iPad, but I do own an iPod Touch and know that advanced games with console/PC quality graphics can suck up the battery quickly and I'm sure it's very similar on the iPad. Your best bet is to turn the brightness down. The lower it is the longer your battery will last. I don't think there is an exact name for them, but they have battery packs you can buy that plug into the charging port. If you used one of those your iPad would take power from it and only use your iPad's battery once it ran out. If you had one or two of those charged up and brought them with you on the plane, then you could just keep your brightness normal (which always looks better) and enjoy KOTOR for the entire flight!
I just realized that the "9 hour flight" was just an example, but those battery packs are nice to have anywhere you go. The prices all very depending on which one you buy and where you buy it of course. Here's an example of one I found on the Apple website: http://store.apple.com/us/product/H9...ttery?fnode=3c