The things to look at most in your pack (some already mentioned):
1. Invest in a lighter pack. It will make your life easier. If you have a small torso, REI has an Osprey Hornet 46 on closeout for $110 (weighs about 600g). Others can suggest better packs for certain, depending on whether you want to go frameless. By itself, this could amount to a weight savings of about 25% of your total pack weight.
2. Clothing-I know nothing about the conditions you'll be encountering, but I looked up some info on Slovenian weather (in August), and it looks to me like you're going to be dealing with temperatures not lower than 8 C/40 F except up in the mountains. If this is at all correct, you don't need to be carrying about 1 kg of clothing in addition to what you're wearing. Look through and see what you can do without at the lowest temperatures you expect.
3. Electronics-You've got almost 500g of electronics, which has got to be more than you want or need. Jeremy's idea of putting the guidebook on your phone is a great idea and will save you another 340g.
4. I wouldn't depend on rocks for tent stakes, but instead buy aluminum or titanium ones. A set of 4 titanium stakes will definitely be under $15, and will weigh in the range of 24 grams.
5. First aid kit and toiletries--Go though what you really need, and you'll be able to cut out at least 250g.
6. You're right about the bladder- switch it out for plastic gatorade bottles or similar, or spend $20 or so to get Platypus bottles which weigh even less.
All in all, it should be very easy to get this pack weighing less than 5 kg, or even 4 kg if you make some sacrifices.