Grass isn't the only surface that you can train on. You can train on concrete, stone, dirt, etc. Saying "there is no grass where I live", is hardly what I call an excuse for not training outside. I guarentee you that there is somwhere that you can train, whether it be a sidewalk, street, dirt road/path... almost everywhere is avalible and suitable.
I am not discouraging training inside, and I do have a few drills you can do. First of all, the juggling is good. Maybe you could try to get into freestyling
? It is a fun hobby, and it helps with your skill tremendously. For a drill, what you do is put various objects around the room, and dribble at full speed and executing moves until you have them down. You have to really pretend that these cones, chairs, etc., are defenders, and you have to pretend that this is a serious game. Really get into it for full success. I don't know if You can use a wall of this room to bounce the ball off of, but if you do, you can do Expert's wall drills
. Daily you can be doing Iwannagopro's Excercises for Improving Touch
and JDefoe's Home Dribbling Program