There are lots of ways to do that and, if you advanced the time-line enough, there is no need to re-gather the original cast.
That right there is essentially a soft reboot. The line between a distant sequel (Star Wars VII) and a soft reboot (The Incredible Hulk) is a blurred one.
As to whether JP needed a reboot (regardless of if JW is a reboot or not), I'm fairly indifferent. Like I said, the appeal, at least to me, of the franchise is not a particular plot arc or character(s), but rather the concept and the setting.
What matters is the dinosaurs. If they do the dinosaurs well, then I couldn't care less about Dr Grant, Dr Malcom, Dr Sattler, InGen or the Hammonds.