From my own personal research and talking to my psychiatrist there are no meds for decrease negative symptoms. My psychiatrist told me the best thing you can do is develop a fixed routine and try to make it habit forming. Humans are naturally creatures of habit so this could work, but it may be hard to start it.

Personally my boyfriend helps me with personal hygiene and cleaning. He gets me to brush my teeth and shower, but I try my best to do these things on my own. Maybe if a family member helped you with keeping clean that could benefit you.