Do you mean what will happen to your existing waypoints after you update your chip? If so, then yes your waypoints will remain saved after updating your chip.
What I did to be extra sure though was to backup my existing waypoints from my GPS chip to my computer using Basecamp and then I uploaded these into the web app also. This way I have them saved in Onx and I also have the gpx file saved on my computer itself in case anything happens.
Onx has a link that discusses this:
Learn to import and export onX GPX or KML files. Your hunting data is yours, and onX makes it easy for you to back up Waypoints, Lines, Tracks, and more.
www.onxmaps.com
And their customer support is really awesome if you wanted to ask them specifics on what happens when you update and etc.
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As an aside if you've got 7 years worth of hunting data you don't want to lose on your current chip/GPS, then definitely back it up. You don't need Onx to do that, if you have a Garmin you can use their Basecamp software for free