Does CI Baseline and the CI Variance Report track changes from the original baseline, or does the baseline need to be updated after each import?
You should not need to re-run the baseline to pick up the changes; in fact if you do that, it does not pick up any variance since the new configuration is now the baseline. Both the 'Show Variance from Baseline' function on the CI record, and the CI Variance Report pick up changes to tracked fields from the current baseline. You also need to run the 'Run Variance' quick action on CI in order for the report to update; the in-record function does not appear to require it (or is running its own version). There is also an OOTB workflow under Schedule Entry to run the Variance for all CIs under change control on a schedule.