how can I get a Restrictive Covenant changed?

One of the ways a restrictive covenant on property may be deemed invalid is if, after the passage of time, circumstances have changed such that the purpose of the covenant is obsolete or there is some other reason that warrants lifting the covenant.  In some cases, a covenant can be deemed waived if it has not been enforced.  An experienced real estate attorney or, in your case, restaurant lawyer, may be able to review the covenant and examine the surrounding facts to determine if there are grounds to have the covenant changed or lifted entirely.