Not too long time ago, i stopped focusing on my dreams and trying to achieve lucidity because i was busy with many things. Now i have been trying to get back to dreaming and remembering my dreams but nothing helps! Do i have to start all over again with the dream journal or does it pick up at some point 
I think you’ll have to build up your dream recall… I guess you should start up with the DJ again.
You just have to want to and your DR will come back in no time.
Try to read other people DJ’s, may be it will motivate you.
Read soe books about LD, its full of good advices.
I would start over, because you will get better results and for you it shouldn’t take long as you know what to do and will pick it back up with ease.
Maybe do the DJ for 1-2 weeks and if everything like dream signs have stayed the same just carry on with the same RC that helped you LD before. 
Why not just start back up with the dream journal? Getting back into all of the old habits that made you successful before seems like a good bet.
I had several days where I was sick and unable to DJ due to awful recall – personally, I really missed it! Try not to view it as too much of a chore. Non-lucid dreams can show you some surprising, very cool things.
Start with basic things, like you didn’t learn anything. Try to raise your general awareness and also try to motivated yourself as much as you can…