While I admire Bud Light's advocacy of adopting rescue dogs, I think this blipvert sends the wrong message - that you should get a rescue dog so that it can slave away for you.
I wouldn't be surprised if the off-screen sequel (Life goes on even when you're not on screen, remember.) went horribly dark, and Weego killed his master.
But leaving aside that editorial opinion, I think this reincarnated human could have been a butler or manservant in his previous life.
And it would have to be one who has already joined the Choir Invisible, which would leave out TV characters like Benson DuBois from 'Soap' and Geoffrey Hudson from 'Fresh Prince Of Bel Air' and 'The Bold & The Beautiful'. (Yes, I believe both characters played by Joseph Marcell were the same man.)
But here are a few other candidates:
Max ('Hart To Hart')
Higgins ('Our Man Higgins')
Mr. French ('Family Affair')
And keeping with the literary turn taken by the "As Seen On TV" showcase this year:
Jeeves ('Jeeves & Wooster')
Bunter ('Lord Peter Wimsey Mysteries')
Passepartout ("Around The World In Eighty Days")
Mr. Belvedere ('Belvedere' was a novel before it became a series of films starring Clifton Webb.)
Plus from the comic book universe, adapted for TV:
Alfred Pennyworth ('Batman')
If Cantinflas had been the Passepartout of the TV Universe, I may have gone with that option.
But I think because he looks like a scrapper, I'm going with Weego being the reincarnation of Max from 'Hart To Hart'.
Most of the others are far too British to be such a mutt. (Although Higgins might have come close.....)