The above suggestions are all good. However, if you absolutely must redirect a POST, the only way I know of to do it is to generate a form consisting of hidden input fields containing your data, and then using some Javascript to auto-submit the form upon loading.

It is no more secure than using a GET request, and much less likely to work. Use at your own peril. A much better idea would be to figure out a way to keep your sensitive data server-side and/or encrypted, as suggested above.