I’ve just read this, unfortunately after doing it.

One thing that should be noted though and that’s that if you’re currently using a sealant like Stan’s you shouldn’t mix it with this stuff as the two are incompatible. Instead you’ll need to thoroughly clean out your rim and tyre and start afresh.
Read more at http://dirtmountainbike.com/products/fresh-produce/fresh-produce-continental-revo-tyre-sealant.html#jqfbQSd54t174PQy.99

Completely forgot I’d used stans on that wheel, it was a bit dried up so I went for a top up, hoping it would fix the softening I was experiencing, not actually going flat but going just too soft and draggy.

What can I expect anything, do I need to clean out and start again?

Of course you’re going to die, we all are at some point.

Clearly the use of the word “DIE” is whimsical short hand for ‘experience any unpleasantness that should be avoided if at all possible as a result of afore mentioned act.’