Juice in general is not good for babies teeth and should be avoided as much as possible. I would keep offering water only. I know it's not exciting and some babies will spit it out, but really at this age they don't know the difference between juice and water, so might as well offer water, kwim?
Have you tried different cups? Most sippy cups have valves so they don't spill but it does slow down the flow and sometimes make it hard to suck the liquid out. Different cups work in different ways so sometimes it's just a matter of trying until you find one your baby likes.
I think bottles are left for milk only, and juice is best left until at least a year or even older.
HTH