Need a tallis be worn for mussaf (for example if a person took it off after shacharis knowing that they’d only be able to daven mussaf later on)?
If so, should a bracha be recited?
The Tallis is traditionally worn for the entire Shacharis service, including Mussaf.
There is no obligation to wear the Tallis for Mussaf, having recited the berachah and worn in for Shacharis, but if davening with the congregation one should wear it like others.
If davening alone, there is no need to put it back on.
A berachah is made after a significant hefsek upon putting the tallis back on.
See Shulchan Aruch (8:14), Mishnah Berurah (8:37) and Biur Halachah.