Two separate questions. 1) How do you trace your app's rank? I cannot find it in itunesconnect. I don't even know how many ranks for one app. 2) How often you update your app? One guy form itunes support team tells me every time an app is updated, it will rank the first in 'Newly Released'. Is it true? The good thing is, I can keep my app exposed by constant updates. The bad thing is, other people would do it also, and my app may be quickly buried. Is Apple encouraging constant updates, or meaningless updates?
1) A lot of people use MajicRank. Another place that does it is AppAnnie too. 2) Yeah updating your app now puts it back at the top of new releases I believe. That's a recent change, for a while it wasn't doing that, and now it looks like that's how it's working again.
I recommend AppViz It's not the cheapest option, but it's worth it. Support is great, it's updated regularly. And besides your ranking it will download all the reviews and sales reports from iTunes Connect.
I have applyzer(1 Pound/month), appannie(free), & appfigures(Free or $5/month) installed. The one I like best is appfigures but it is missing one key element the other two have which is a features summary page(where and what rank you are in featured areas). However appannie gives this for free so you can supplement appfigures with appannie if you wish. Appannie gives a lot for free but requires lots of submenu clicking to view different countries. Applyzer is an excellent low cost option at less than $2/month. If it got a UI makeover it would be on par with appfigures. Appfigures will give you a 2 week trial before you are given the free/premium option. For me at $60/year or roughly 30 minutes of billable dev time, the actionable data far outweighs the cost. I have no connection with any of the above mentioned, this is just my opinion for any who want to consider it. However I would certainly suggest you get at least one of them installed so you can begin to analyze how/when you update effects how your app is placed in the app store.
Appfigures have been pretty responsive to me in the past when I have made feature requests, so I'd suggest asking for such a page via their support page.
