We have several exterior doors where the sheen has long worn off the
finish.

Rather than stripping off the full layer of finish and stain, I was
wondering whether I could do the following and still achieve a nice
result:

1. Lightly sand exterior to make sure that surface finish is removed
and that surface is smooth and clean

2. Apply stain as desired to "freshen up" the look since some of the
stain has obviously faded

3. Cover with multiple coats of spar urethane.

Will this work or do I need to completely sand off the old finish and
stain to get a good result? (I prefer not to since there is a fair bit
of trim on the door and a complete sanding will take a long time.)

Any other suggestions for refinishing and/or touching up the finish on
a door without having to do a complete scrape & refinish job?

Thanks