Can you resubmit a rejected manuscript to the same journal if you have made many changes to improve the manuscript?
Some journals won't accept a resubmission after rejection. For some others it might depend on the reason for rejection. If the editor deemed it not suitable for the journal it isn't likely to be reconsidered.
But otherwise you should be able to resubmit it. You can also ask the editor whether it would be advisable or not. Follow their advice, of course.
And &quot;frowned upon&quot; only matters if the editor is the one frowning.