We want to improve upon our overall face to face communication. I recommend using "upon" here. It shows there is a project here, and you are not talking generally about communication.

Olga_L, The difference between improve and improve on/upon: improve (trans)....to make better improve upon or improve on.....to make better than; to advance beyond However, overall face-to-face communication can be seriously improved upon. = However, we can seriously advance overall face-to-face communication beyond the email policy changes we made two years ago. Basically, Eliot is correct. "Improve upon" is used to make a comparison with the ongoing project mentioned in the first sentence. --- However, overall face-to-face communication can be seriously improved....This sentence could be construed as a generalization not dependent on the first sentence.

Yeah, you can remove "upon" and still have the same meaning. I can't think of any examples where adding upon changes the meaning of just "improved." I'm pretty sure you can use just improve in any sentence you can use improve upon in.