We learn in Shulchan Aruch Orach Chaim 178 the laws if one leaves the place where they were eating if a new bracha has to be made or not when they come back (or if they change to a different place.) If someone was eating (by themselves, see Sif Beis for why I'm mentioning this) vegetables and left the place where they were eating and went outside and then came back they would have to make a new bracha on what they are eating from before. I would say this is seemingly even if the person had in mind to come back (what seems to be the case there in Sif Beis as well.)
However when it comes to smelling besamim (fragrances) the Shulchan Aruch in Orach Chaim Siman 217 Sif 1 says that a person makes one bracha when they walk into a store that has besamim. If they go in and come out however they make a new bracha unless they had in mind to come back which in that case a new bracha is not made (the M"B in note 6 adds this is only if they had in mind to return immediately.) It seems to be however that by eating even if someone has in mind to return and continue eating in the original place if they walked outside and came back a new bracha would be made. This is not the case of besamim where if one had in mind to come back they wouldn't make a new bracha even after leaving this place. What is the difference between eating and besamim?