I have a Schengen Visa which has Validity from 03/10/2018 to 03/04/2019. The duration of stay allowed was 45 days. I travelled to Greece on 05/10/2018 and left the country on 17/11/2018, hence completing 44 days. Now I have only one day left on the current visa. My husband is a student in Greece which is why I need to go there again and again and stay for the maximum number of days possible. Can I apply for a new Schengen Visa while my current one is still valid but has almost negligible number of days left for me to stay? Please help as I love my husband a lot and the thought of staying away from him till April literally kills me :(
You can apply for a new visa; the fact that the existing visa has a day left on it should not preclude this since it will obviously not be enough for the visit you're planning now.
The consulate may or may not feel they need to revoke the old visa when they issue a new one, but they'll make that determination for themselves. It is not something you need to be concerned about yourself.