@Matija1, I think that the negative aspects mentioned in many of the reviews (I only read the first 20 or so) are probably keeping people away. I definitely wouldn't book the accommodation after reading the first few reviews, especially as a non-smoker. And after reading that the neighbourhood appeared dangerous.
However, on the basis of the photos, you seem to have carried out some extensive renovations, and the place looks very, very nice.
And most of the reviews mentioned that you were a good host, friendly and helpful. The negative reviews were about the accommodation itself.
I would suggest making this listing a completely new one, as if you were starting from the beginning. It's true that you won't have any reviews, but this will quickly change once guests begin to book.
You could mention in the space description that you have carried out extensive renovations in the past x number of months, and you could mention a few particular things. You could also describe these renovations in the photo captions area.
Also, you might want to mention specific cultural and other events that take place in Split at various times of the year. Make the area sound attractive so that people will be keen to come there anyway, and will be glad to have a place like yours to stay in. The location does sound excellent.
I'd suggest you ask for a Security Deposit to cover any possible damage once guests start rolling in. I'd recommend offering a weekly discount as well. This could be attractive to someone intending only to stay 5 or 6 days, but who would extend the time because of the discount.
It would be very useful to have House Rules, as guests need to know exactly what is expected of them. In your case, I would recommend No Smoking inside the premises. You could also indicate whether you welcome children and animals. And also make it clear that no more than 8 persons are allowed. I strongly suggest that you read other hosts' listing to see what kinds of things they have mentioned in their House Rules.
It's also a little odd to see the space can sleep 8 people, but you charge $25 a night for 1 person, with $18 for each additional guest after the first one. This would amount to $151 per night. Since you're not likely to have just one person booking the apartment for her/himself to stay in alone, perhaps give a bulk price for up to 4 people (e.g. $100), and then charge $15 for each additional guest after the 4th guest.
I'm just thinking out loud here. They're simply random suggestions. 🙂
I also recommend cutting by half the number of photos. Stick with just one or two good ones of each section of the apartment, with perhaps a couple more showing an interesting part of the environment.
I'm sure others here will have excellent suggestions. 🙂