It's possible that your nutrition requirements are too strict to get much food variety. Your food filters could also be too strict for the number of recipes we currently have (we have thousands of recipes curated currently and are always adding more).
Here are some suggestions for improving variety:
1. Adjust the meal settings. Open the left sidebar menu and select Meals under Plan Settings. You can click on the name of each meal to open its settings and make adjustments as needed. Increasing the Available time and setting the Complexity to Any will vastly improve variety.
2. Set your generator focus to variety. Open the left sidebar menu and select Generator under Plan Settings. Set the "Generator focus" setting to Variety. This comes at the expense of grocery efficiency and macro accuracy, so you'll have to decide if the trade-off is worthwhile.
3. If it's the meal or food regenerate buttons that aren't giving you much variety, it could be because the generator is looking for a pairing of foods nutritionally similar to the previous meal and there aren't many available combinations. Try mixing up the other meals a little and coming back to the original one.
4. Make your food preferences less strict. Unless you're trying to go strict vegan or paleo, try selecting the "anything" diet type, and then only exclude foods you definitely can't have, or don't know how to substitute. Then, if recipes come up with an ingredient that you don't like, see if you can make a diet-appropriate substitution that has similar nutrition (e.g. butter -> olive oil, wheat bread -> potato bread for gluten-free).
See more about making substitutions here: How do I modify recipes?