You will have to re-paint. 5 years is a long time, dirt accumulates on the surface, it fades, ect. You will never get the new paint to match the old.

I always buy brand name paint from a paint store that keeps the color reference on file and have had excellent results with touch ups done years later. I painted my living room 10 years or so ago. I recently had a leak in the roof which caused some damage to one wall. I bought a small pot of paint and began by doing touch ups. I was convinced I would at the very least have to paint the entire wall but no. Touching up was enough. The moral of the story is buy good quality paint from a paint store. It is often the same price as paint in a big box store and you are sure to find the exact same paint later.