I’m making some assumptions, because the screenshot doesn’t show what you’re doing in your timer code.
My main assumption is that you’re refreshing the repeating panel items with something like:
self.repeating_panel_1.items = anvil.server.call('whatever')
Basically that you’re resetting all the items every time the timer ticks. If that assumption is true, then there’s no way to preserve just one field across the rows. That field will get reset along with the rest of the items.
I can imagine a couple of approaches to maintaining the value in that field, but they boil down to converting your search results to a list (that will lose any paging benefit, so if you have a lot of results it might be slow) and then merging that list with the items property, so for those items already in the repeating panel you maintain their value. You might be able to do that inside items itself (e.g. prepending the newer items, since you seem to be ordering by date/time), or you might need to build a new list that’s the merged one and set the repeating panel’s items property to it.
Hopefully someone on the forum’s done this very thing before and has some nice code to share as a starting point.