I have totally sanded and refinished Bruce flooring 2’s & 3’s with walnut pegs before. While this is a last resort it may be the best solution. The question is how much of the floor does “some places” involve.

If you lightly sand and refinish individual boards and recoat them the problem is matching the coloring the aging process has created in the surrounding boards. You can use blue masking tape to isolate the finish to individual boards when recoating. If I were choosing this option I would use an oil modified urethane with a semi-gloss sheen.