Prep Ahead: Combine the lemon juice, oil, garlic, capers, artichoke hearts, and chicken in an airtight container. Refrigerate for up to 1 day or freeze for up to 3 months If you want to prep this recipe up to 4 days in advance and keep it in the refrigerator, keep the chicken breasts in their original packaging and consume before the best by date (refrigerating them in the acidic marinade for more than a day can make them tough.) If frozen, thaw the ingredients in the refrigerator overnight before adding to your slow cooker.