I would call the court, explain why you need your court date moved up, and if they find the reason compelling & if the have space on the docket, they have the ability to move your court date. Make sure you call the correct number/circuit/division that your particular case is in. The court will have staff that can answer your question. The court may require a formal motion. Many states have motion forms available for simple motions such as these for pro se litigants (people without an attorney) to use.
To get your court date moved up, contact your local district attorney and explain your circumstances of your misdemeanor offense being dismissed due to participation in the merchant restitution program in TN and ask them to agree to move the case to an earlier date.
Most of the time the local court will accommodate your request to get your court date moved earlier in Tennessee.
If this is a matter of misdemeanor theft at the Shelby County Criminal Justice Center (201 Poplar), due to the volume of cases handled, it will be very difficult for you to do this on your own without a lawyer
If you hire a lawyer for your petty theft case, he or she should be able to have the matter advanced on the docket. It is not difficult to move your court date up in TN if you know the procedure but you will likely not be able to find court personnel who can take the time to do this for you.