While a "kit" should (one would think) have the yeast and any other chemicals matched to the anticipated pH, sugar level, and nutrient needs ... my first curiosity would be whether the pH (one of the measures of acid in the wine) was too acidic for the yeast.
There are times when, as the yeast does it's thing, the wine actually becomes more acidic as it ferments ... and can become so acidic that it stalls the fermentation ... other factors come into play too, but the acid/pH is a common one in a stalled ferment.
If this is the case then a yeast strain that didn't like it the first time would like it not much more the second time, assuming any new packet of yeast you might add is the same type. In general, no, you do not want to just add more yeast ... both for this reason and also because the final wine can be negatively affected in a number of ways by adding lots more yeast than the directions indicate.
As far as adding additional nutrients, as the SG drops, the window of opportunity to add nutrients gets smaller and smaller. If the yeasties are nearing the end of their lives, they might not have time to eat all the nutrients you might add and this would result in excess, unused nutrient floating around in your wine which also invites other problems.
While you could potentially add a fractional dosage of nutrients, as long as your wine is currently fermenting, I would just leave it be.
Did your wine kit include nutrients to begin with? ... did you add them as per the directions? ... did you go buy other nutrients at the brewer/vintner supply? ........ it is a little curious that the kit stalled. In any regard, if it was me I would avoid adding nutrient at this point.
One other thing ... you said this is a Chocolate Raspberry Port.
Port is a very specific type of wine and not one which is as simple as some other wines.
I assume they are not just giving you juice concentrate from one of the 5 or so types of grapes that are commonly used in making port without the rest of the elements for making the wine such as oak chips, and particularly good detailed directions, and possibly the distilled spirits (liquor) which you are expected to add to the fermenting wine to kill the yeast and leave the wine with enough sugar to be a “sweet” wine.
Port is a “fortified” wine ... you add liquor to *kill* the yeast at some point (taking SG readings is how you determine when that is). The directions would be very specific about all this. This kit would be one where you want to follow the directions very closely.
But that having been said, the fact that this is from a pre-established kit, and that it has apparently resumed fermenting, and that you are actively keeping it in a temperature range which the yeast likes ... I would think there is a good chance your wine should finish up fine. Just follow the directions very closely.
![Craft A Brew - Safale S-04 Dry Yeast - Fermentis - English Ale Dry Yeast - For English and American Ales and Hard Apple Ciders - Ingredients for Home Brewing - Beer Making Supplies - [1 Pack]](https://m.media-amazon.com/images/I/41fVGNh6JfL._SL500_.jpg)
