I am also trying to fit in improvisation practice. I volunteered to go fairly early for my improv exam - 30 April. Leaves more time later for the other things I have coming up.
Also doing position work (various studies by people like (Mazs, Hohmann and Scholz) and technique (vibrato and bowing). This is all helping.
i have ordered some more books on bowing (both from the Library and Amazon) - keeps me motivated.