Hey Mariko. To answer your question, you keep the bow moving up bow for the staccato slur. To add more to Elizabeth’s response, ideally you should have your finger on top of both strings (like you would do for a double stop), but this is difficult for many beginners. What you can do instead in most instances that don’t have a staccato (Elizabeth is right that the pause helps in this instance) is to rock the finger over slightly to create proper contact with the adjacent 3rd finger. That is actually would I would naturally do in this passage, but it would be more proper to have it on both strings with good contact (like a double stop). Thanks for the post and questions!
Thanks Elizabeth for helping with student questions!