Back in Volume 3 the tragedy of Penny Polendinas death occurred. After this many people assumed that she was now dead, but is she really? If you recall, Penny was from Atlas (remember this) and during her death we saw a glimpse of what appeared to be her creator or "father". Now, in Volume 4 and 5 Penny was said to be dead, but I disagree.
Penny is a robot. Robots can be rebuilt. When Penny died she was "beheaded". Now, like humans, I would assume that Pennys memories would be stored in her head. When Penny died she was damaged at the neck, but her head, the place I would assume her memories/information would be stored, seemed to be intact.
Going back to what I said earlier, Penny is from Atlas, as well as her creator. In Volume 7 the gang has returned to Atlas. This is where I think we will end up seeing Pennys return as she will be in Atlas somewhere and someone from the gang will see her. How will the they see her after she died? Well I would like to think that after her creator saw what happened to her he ended up going, or sent someone else, to retrieve her remains. When her "remains" (not sure if that is a good term to use?) arrived back in Atlas I think that she ended up being rebuilt and her memories were restored since the part of her head where a human brain would be was intact.
Now, I do have a possible extension to this theory. There is a chance her creator could have wiped all of her memories for her safety or may have removed her memories of team RWBY, therefore if someone from the gang sees her and goes up to her she might be confused or startled.
Any who, this is all a theory and something I would like to see in RWBY Volume 7. If you have any input or if you got confused by some stuff I said then feel free to reply with whatever!
Thank you for reading! Have a wonderful day!