In reply to fluffy bunny:
Having broken my ankle bouldering indoors twice, I have a healthy fear of falling, and if I haven't bouldered for a while it gets worse. Fear is healthy and normal, you can get injured doing this stuff.
Exposure is the thing that helps me. If I go back after not climbing for a while, I will often not want to do the top move of anything but the easiest problems. I often spend the first few sessions back spending as much time high up on easy stuff as I can, sometimes just going up and hanging around or traversing high to get used to it. Combine that with working on some harder stuff low down. Eventually, you'll get to a hard move higher up and just do it without even thinking about it.
Having said that, I always down climb when I can, and if I can't, I down climb as far as I can, then hang and drop.
One of my other tactics is if there is a hard or balance-y move at the top of a problem, I will often work the rest of it and get it dialled, then come back for the top move next session when I am fresh and don't have to spend energy figuring out the rest.
Lastly, even when you are a bit worried, try to climb with conviction. You are far more likely to come off unexpectedly by doing something halfheartedly than you are if you give it everything. I know it can be hard to do, but moving positively really does seem to help.