Can I replace just a section of the roof caulking?

[Kehmna]

I am new to my 2015 Bambi 16 and in giving it a good cleaning today I noticed a section of the roof caulking that was not adhering. My question is how to deal with the small section. Can I shave away the loose edges then caulk over the exsisting caulking or, completely cut away the area and recaulk or, do I need to completely remove the caulking from the entire seam. The rest of the caulking is still pliable and adhering well. Thank you in advance for sage advice.