If you find that your policy is inadequate, can you upgrade your policy during the middle of the year?
Typically you can't change a health plan after enrolling, however on ObamaCare's Marketplace plans you can adjust the amount of cost assistance you get. Cost assistance can be adjusted based on income or a change in family status (typically when people would be added or subtracted from a plan). Adjusting cost assistance won't change your benefits, but it can change the total you spend on healthcare throughout the year. No one will pay more than the maximum for covered services, so this can help.
You can also change plans via special enrollment if you experince a qualifying life event.
Aside from that, you typically will have to wait until the next open enrollment period to change plans.