Unfortunately, laminitics are better kept off grass during the day and put out at night. The fructan concentrations in grass during the day in the growing season are what cause laminitis. There can be other causes, as I have described before on this forum, but where we are talking about grass, fructans are the enemy.
Strictly speaking, as long as the rotation has not been so severe as to cause the pedal bone to penetrate the sole, there is hope for your mare. However, once rotation has taken place, very stringent management and proper care of the foot by a competent, attentive farrier, possibly in conjuction with regular veterinary assessment is very important for a good prognosis. Left to chance, with anything other than a proactive management regime, there is always the chance of a recurrent problem.