However, if someone is happy to just plough on as ever, you have to be more creative. Apart from anything else you'll need to check that they realize that their remuneration is also likely to be static. Too many people seem to think that investment in training will just lead staff to move on to new jobs. I'm sure this started out as a joke, but too many skinflint, humorless managers took it straight. This means that training should be a key component of the job plan.
Objectives are a good way of deriving training requirements, so they go hand in hand.
By comparing personal targets and known skills, you can see where training is required. But it is also important to remember that you may need more personally oriented skills. There is little point in learning something without a practical application behind it, you could make a group presentation one of the deliverables for a performance review. Many technical people are also reluctant to speak their minds. This is especially true in companies where conformity is highly valued.