I'm spending about an hour total per day on maintaining my Spanish and German. Both are in the B2-C1 range. I'm maintaining by reading, listening, watching, conversing and a very minimum of writing. When an interesting word or phrase catches my attention, I might look up a definition or look up the grammar structure. I can comfortably use monolingual reference materials at this point. I am terribly lazy when it comes to writing.
This year, I'm focusing on slooowly learning Russian from scratch (about 90 minutes per day). Since January, I have learned to read and write the alphabet, and basic grammar and vocabulary (200 words or so). I'm using Pimsleur and a variety of other materials such as high school text books, Russian World youtube videos, etc.
My goal at the end of this year is to be at a solid A2 level. Russian is beautiful and interesting, but definitely a challenge. Knowing German helps.
I also have a TAC log on HTLAL as BAnna.