Buy a cycle computer for your current bike if you don't have one.
Start looking at bikes now, sitting on and riding as many as you possible can.

DO NOT BUY A NEW BIKE UNTIL YOU'VE DONE 500 miles.

By looking now, you get a good feel for what is out there and what isn't. You'll fine tune your bulldust detector. Sooner or later, you'll find yourself walking into a shop and going straight to one style of bike or even a specific make and model - that's when you'll know what your heart is telling you and to be honest, that is all that really matters.

The 500 mile bit (easier for me because I did 500 kms and kilometres are shorter ) has three purposes. Firstly, by forcing you to wait while looking, you look effectively - ignore 'special offers', there'll be another 'great deal' in a month's time. Secondly, the distance allows your body to put on some condition. Third, it allows you to work out what sort riding you're actually doing as opposed to what you think you'd like to do - the two are usually wildly different, especially with regards to time and distance.

Richard