Should i change my trans. fluid?

i have a 2004 Chevy astro with 94k miles. the trans is starting to slip when cold, and the fluid is brown and burnt. im wondering if it is too late to change the trans fluid. i have heard of people with bad transmissions changing their fluid, and the car never moves again. as far as i know, this trans. has never been touched. i bought it with 48k, and never did anything to the trans. i would like this trans. to go a little longer if possible. please help. thanks.