It depends. If you find that it joined on a fast data rate (like SF7) then its range will be limited. So, it may work close to that gateway, but not in other places. Now, assuming the device has ADR enabled, then after a lot of failed uplinks (96 messages) it may lower its data rate by one step and try again (for another 32 messages), and so on. Hopefully, at some point it will succeed. But that will take a long time. In such case, it might be better to re-join, so the device may start afresh with a slower data rate. (During an OTAA join, many devices will lower the data rate until the Join Accept is received. That will also take time. But not a whopping 96 messages. I don’t know the device you’re using though.)
But, in your case, you don’t know what data rate it’s currently using. So, first doing some investigation while you know it’s still activated, may help.
Aside: given that it joined at least once, you’re sure that the settings in TTN Console are okay.
…or just go on some nearby wide road, to avoid buildings from interfering too much. Look at that other map I linked to above (though that shows old mapping details). Any red, orange or yellow dot proved to have a good reception some day in the past, so might work with your current settings.
Aside: when clicking an item in TTN Console’s Data page, you may also want to look at which gateway(s) received your uplink. And did you talk to anyone from your local community? @ltfe & friends may have some insight, or may lend you a device that you can use for some up-to-date mapping? Their gateway surely looks positioned well!
(I don’t know if adding a gateway will help. Especially not if it’s an indoor gateway.)