Your reply to “Yup” will depend on the context that which “Yup” is used. If the context is an answer to a Yes/No question then you can say something like “ok” or “great”.
Have you talked to your father?
Uses of Yup and how to respond
Your reply to Yup will depend on the context that which “Yup” is used.
Yup as an agreement
When “Yup” is used to simply agree with something, your reply can be anything really. You can decide to change the topic or continue with the same topic.
My football team is the best.
They won the game last night 5-0.
Yup as an answer to a Yes/No Question
You can reply to “Yup” that answers a yes/no question with “ok” or “good”
Did you clean the garage?
Ok great, Now clean your room.