Should I transplant my dogwood?

I've put a native dogwood into a half barrel, transplanting it from a regular terracotta pot. It has been doing fine for the last 6 or 7 years, but it is still a young tree, blossoming for the first time last year. Will I keep having good luck with this for another year or two, or should I plan on making it a transplant this fall?

 

I would get on it as soon as possible or otherwise the fall.