Please try this and report back. No guarantees...
In the Do Nothing Step (which seems to be where you want to reset the counter on the second dataset), add a Scripted Assertion above the Scripted Assertion that is currently in your model above.
In this new assertion, name the assertion ResetAccountBalance, set the assertion to fail if the result is FALSE. Then, try adding the code:
testExec.setStateValue( "lisa.getAccountBalanceWidget.reset", true );
return true;
Here are a few reference posts that might help:
https://communities.ca.com/message/241888669?commentID=241888669#comment-241888669
https://communities.ca.com/message/241881496?commentID=241881496#comment-241881496
The last post, above, seems to have had questionable success -- perhaps, version dependent or a deprecated feature.
If this were to work, you could add your conditions in the same assertion to determine whether or not you want to reset the dataset counter.