You need force drain, or master force drain, or whatever it's called. The power that lets you drain force from your opponent. It's a really long time since I played this game. Anyway, you need to have it, and I think at 'master' level for it to work reliably. If you're already in the cave, kill a few rounds of beasties with a lightsaber until you can level up once or twice, enough to get this power. And make sure that you never drain your force points down to where you don't have enough to cast force drain, because then you're stuck.
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I only exploited that one time but I didn't have a problem with my force not recharging. I was playing DS so maybe it's only LS players that don't recharge force...