Hey,

I want people to answer the same survey multiple times.
I hope to be able to add a link to my 'End Message' that brings them back to the start of the survey and allows them to start again.

Can this be done easily so that Limesurvey 'forgets' that the person associated with this IP address, or with this cookie, has already taking the survey?

Hi,

is'nt the End URL (Settings > Text elements > End URL) an option for this?

You can either call this (i.e. the URL of your survey) automatically (Settings > Presentation > Automatically load URL when survey complete) or give the option to call the URL manually,

Yeah, might be, but which URL should I call for so that the answer the person just gave are stored and they are presented with a fresh, new empty survey to fill out again?

The same URL as your survey has and append "&newtest=Y"

Cool, but I get the screen where I need to register again.

If I already registered to take the survey with my email address, can the URL also forward me so that I do not have to register again to take the survey a second time?

You can start a new session by adding the parameter newtest=Y to the survey URL.

Regarding skipping the registration page, try appending the token to the survey URL - token={TOKEN:TOKEN}

The survey will have to be non-anonymous and you will have to enable "Allow multiple responses or update responses with one token" - www.limesurvey.org/manual/Participant_settings

as the token will change from user to user, I assume that adding "token={TOKEN:TOKEN}" to the url will auto-insert the token of the active user?

So the entire URL will be:

Yes and yes.