on a launch monitor (ideally with a PGA pro who teaches with one - a GC2 HMT as that also gives you the important factor of strike location on the face the single most major factor that influences everything else)
find what the norm launch angle is along with the spin rate and the other parameters of angle of attack, path, face angle at impact and speed
then try out some other drivers to see just what #'s they produce
much generalized rule of thumb but if the strike pattern shows missing center pretty regularly by a bunch or so then likely to be a deal better off staying with a driver model that's going to give the most possible assistance with off center strikes
but as a rule, although I get not as exciting as buying a new driver ...... the biggest bang for you $'s would be getting lessons on a launch monitor to be able to deliver better launch parameters with the existing driver - a new driver is not going to make up for strike issues any ways much
as if you getting very high launch with a dead flight not so much distance then the strike location is going to be coming from high up on the face, nearer the crown than the middle of the face
buying a cheap can of either dry shampoo or foot spray and spraying driver face hitting a bunch of 4 to 6 shots (after having warmed up first off through easy wedge, easy 7i's for a time to get the best tempo/rhythm and balance to the swing motion)
will identify the issues goin down with strike location that lessons would help begin to address
