Hi,
As far as I know, there isn't an update to the TS19 early access version.
There are a couple of updates for the beta version...
To check for updates, start the launcher, then check install option.
You should check that your username and password are correct, then you'll need to select the correct update stream.
One minor point is that TS19 doesn't show up in your list of trainz purchases - you need to use the same username for the version as when purchased.
Regards
Colin