Currently the ability to retest a journey is very limited due to the strict limitations on repeats. While this is understandable in a production setting it is very frustrating when trying to test a complex (or any) journey as you have to wait for a day to evaluate the result. There are various options that could fix this and they are all applicable to both CRM and Marketing Automation, both of which are lacking the ability to ring fence testing.
a) Provide the ability to setup a test bed from which testing can be done. Restrictions such as repeats will be lifted when working in this environment
b) Provide the ability to create what-if scenarios. This is a very common approach used by software vendors that allow user to create an isolated environment in which an alternative truth can be modeled. Tried and tested scenarios, or parts thereof such as rule, journeys,etc. can then be imported into the production environment.
PS. Testing should not be performed with work around such as using a evaluation account with limitations.