What does it mean shooting up every day? She probably isn't doing it every day. Shooting crystal meth is rough, it's hard to keep doing. At my worst I could only do it 3 days in a row. The lack of sleep is what gets you, after a few days you should be able to tell something is wrong with your friend. She will also stink, like smelly feet plus caustic chemicals. Meth isn't like heroin, you can't keep doing it every day and maintain. With heroin you don't need to take a break, you don't want to take a break. With meth you have to or else you will fall apart. Those meth heads you see in videos doing a weird sort of dance are because of this. Lack of sleep also causes intense paranoia. Meth also makes it hard to eat or drink, and dehydration can be a big problem with all those toxic chemicals you need to pee out. When I wouldn't drink enough water I would get these weird chemical burns on the tip of my tongue.
You can't force her to stop, all you can do is make sure she is safe. Get her a narcan kit. Crystal meth is actually one of the safest drugs right now because it is so difficult to cut with fentanyl. Weed, ice, shrooms and a few others are safe from the fent but all pills and all powders are dangerous right now. She will be taking pills to deal with the meth wearing off. It doesn't have a comedown like coke or MDMA does, but all the stress you put on your body will suddenly catch up with you and it will feel like a comedown. Xanax is great for this, but Xanax is the second most faked pill behind roxicet.
She also needs clean needles. I know this is a very touchy subject but it's very important. Needles are extremely dull after just one use. By the time it's a week old it will barely pierce her skin anymore. That will do a ton of damage and greatly increase the chance of abcesses. After two constant weeks they aren't really use able anymore. When you are all strung out you won't really think twice about using someone else's rig if you have no other options. HIV and hepatitis are both very common in circles like this. Unfortunately politicians, like our ex vice president, love to go after needle exchanges. They shut them down in Indiana and it caused a major outbreak of HIV.
My problem was more with heroin, not really meth. So I can't tell you how to solve this situation. If you can't solve a drug problem then the next best thing is "Harm Reduction".