pics ? but id keep going til that mother fucker is super dead, like on its side dead before i ever quit. dont ever give up ! how far into life is it ? lol how old?
http://forum.grasscity.com/advanced-growing-techniques/291687-bonsai-mums-guide.html look through that guide. It shows when they deliberately screw up the plant in order to push it to it's limits. you'll be fine as long as you fix your problem are you flowering or veg'ing check your ph when did you feed last? are you checking your water's ph? where do you get your water from? what does the die back look like?
Oh god...uh i was kind of winging this one and didnt take many precautions. Thats why im not surprised its dying. All i know is ive kept it well watered and its in the flowering stage. I use tap water, if that helps.
If the pH of the tap water is too high then your plant has suffered nutrient lockout. Over water could be a contributing factor as well.