I would not advise to open an Update set that you have already closed in DEV (unless immediately). If you have multiple developers and they may be working on the same configuration, it can be impacted.

The safest way is to create a new update set with suffix "... - 2" so you know its the 2nd one, and move to TEST once ready. You can keep doing this with 3, 4 etc. if you have more changes required after UAT.

Once the final UAT is completed and you are ready to move to Prod, instead of using batch, what I do is merge all the related update sets into one with suffix "... - FINAL". This is the one that I move to Production.