I don't know of any that do. That's not to say that there isn't one. Most 'conversion' occurs when you switch from term to permanent (most often whole life) insurance. ART is just what it stands for, an Annually Renewable Term policy. If you no longer want the policy, you would not renew it. If you want a level, fixed term, you would most likely be looking at a scenario where you may have to be REPLACING the ART with the level term.
If insurability is your concern, or maybe the new contestability timeframe, your best option may be conversion to permanent coverage.
I am unaware of any ART policies offering conversion to a level term policy. Term policies, whether they are annually renewable or have premiums locked in for a set number of years (5, 10, 15, 20, etc) are typically convertible to permanent policies. There are two types of life insurance: Term and Permanent. Conversion refers to converting from one type of policy (term) to another type (permanent).
If insurability is your concern, or maybe the new contestability timeframe, your best option may be conversion to permanent coverage.