You're getting fabulous reviews on iTunes and on forums such as Touch Arcade. And shortly after Avadon was released for iPad, I think I saw it as high as the 18th top-grossing iPad game on the App store, and it was in the top 25 grossing iPad apps of all kinds, which is really impressive.
That being said, I would strongly recommend that you update and improve the game as aggressively as you can, given all of your other time commitments. Don't put it off until the next game. iOS gamers love developers who respond to suggestions and who improve the game, and they get rather frustrated with developers who never seem to issue updates. The good will and positive word of mouth and the enhancement of your reputation that you will generate by further refining an already excellent game will prove to be a rich return on your investment. I'm talking mostly about user interface refinements, but also performance issues on iPad 1, such as low memory or sluggish performance (if these are issues on iPad 1, which I'm not even sure that they are.)