BBC. Listen. When doctor who isn't getting the viewers you'd hoped for, reduce its budget. Let it be niche, and FORCE your writers to just do self-contained sci Fi adventures with no returning characters, settings, or monsters from previous runs. Keep hiring fresh writing talent.
It saddens me how such an imaginative and creative show struggles to get a season 2, this is one of those shows that's gonna be cited as a main inspiration for movies and games 20 years from now, it's peak sci fi.