Is it worth it?

I have a 21 year old Tag which I've never had serviced. It's never been in water and I've taken good care of it. Understandably, it takes more juice from the battery to run these days. I have to replace the battery at least 1X a year now. It's stopped working twice in the past several months. Is it worth spending the money to have it serviced? From what I've seen online I wouldn't send it back to Tag but most likely would use a local jewelry here in the Washington, DC area. Any advice would be appreciated.

Batteries should last longer than that. Either it needs a good clean up/oiling or, more likely, the whole movement would need replacing. I don't think there's any issue with sending it to Tag - they'd do a great job with authentic parts, but you may baulk at the price.

Looks in great condition, I'd get it fixed up one way or another.

Are you using batteries from a well known brand, and, having them replaced by someone trustworthy?

Isolate the battery issue first.