How to refinish indoor window molding wood?
Refinishing it by stripping / sanding off the existing finish, restaining and resealing, would look great but a lot of work.  

If it was older, rubbing it with fine steel wool and some finishing oil can make a beat finish look pretty good, though way short of refinishing.  At 25 years old, it was probably sealed with polyurethane, which doesn't rub up as well.  Still, it's worth a try.  I doubt it will make it worse, but still try it on a limited area first to be safe.  

For the oil, there are many to choose from, one that no purist would approve of but works pretty good is Scott's Liquid Gold.  

Since this method doesn't add any sealer or color, it won't make refinishing any harder if you have to bite the bullet.