You would need to file for a Modification of your Chapter 13 plan. When someone files a modification to the Chapter 13 plan, the Trustee or Judge may not approve the plan or modification based on non-feasibility of the plan. In other words, this means the proposed modification would not succeed.
In order to confirm a plan, the court must find that the debtor will be able to make all payments under the plan and to comply with the plan. The court will rely on the Chapter 13 Trustee to determine whether the plan is feasible. Red flags that a plan is not feasible: when the debtor's budget on its face reveals insufficient disposable income to make plan payments; the budget is unrealistic and does not provide for basic needs (in other words, your living expenses exceed your income.)
There is also a substantial change in cirucmstance test that must be met. Some jurisdictions differ over this test, but safe to say, there must be a compelling reason for the change.
Your issue may be that if your income is seasonal, and therefore not steady, it may not be approved. One of the main factors of a successful Chapter 13 plan is the ability to make the payments on a regular basis.
You should discuss this modification plan with your attorney so they can gauge the best strategy for its success.