I have been living abroad (Ireland, Australia and back to Ireland) for the past thirteen years and my main language at this stage is English. I obviously have not forgotten my native language, French, but I find myself struggling a bit with some vocabulary and formulating sentences (believe me, it gets giggles from my family when I go visit them). I guess this is what happens when even your thought process is in English.
Since I want to keep up with my native language, I make the effort to include it a bit more in my every day life (plus, my lovely Irish husband has been taking lessons to improve his French over the past year and insists on practicing it on a daily basis; this is helpful for both of us!). Here are a few ways to put a bit of French in your life.
Everyday with breakfast, the first thing I do is turn on the French radio France Inter via an app. I listen to the news and topics of the day and have it on as well while preparing dinner later in the day. I can understand though that this would be for someone who already has a few basis of French, else it might just sound like a lot of 'foudefafa'.
There are a lot of good French songs around. I am not very familiar with the more contemporary French singers but I make the effort to research it and I have discovered some great French music over the past couple of years, including Phoenix (they sing in English). I have an ongoing Spotify playlist that I have made public: La Petite Frenchie (I will be adding to it whenever I find good ones - I am only choosing songs in French, not just from French singers but in the language). There are a lot of classics in the playlist that you might recognise.
Reading in French
This would require some knowledge of French obviously. If you are a beginner, I would recommend to read small newspaper articles here and there (I find Courrier International really good), as well as things on the internet (reviews, blog posts, recipes etc.).
You could also get your hands on books that are both in French and English (when I was in college in France and we had to study Shakespeare's Othello for our English literature class, I found such a version of it and it was my saviour, even though the French translation was equally difficult).
As you get more confident with it, you can start getting into novels. If you use such a thing as a Kindle tablet, you can download a French/English dictionary and when you find a word you don't understand, press on it and it will give you the translation.
I read quite a lot so I would not know where to start with suggestions but a few books I think are easy enough to read are: practically anything by Guillaume Musso, comics (Tintin, Astérix), Le Petit Nicolas series (Goscinny and Sempé), Le Petit Prince (Antoine de Saint-Exupéry). And classic 'Le tour du monde en 80 jours' by Jules Verne turns out to be a very easy read as well in French.
The great thing about watching a movie in a foreign language is you can start with subtitles in your own language so you understand what is happening and associate what you hear with what you read. As you start feeling more confident with it, you can move to subtitles in French for a French movie and then eventually remove them altogether.
My list of movies I like is endless so I am going to give you suggestions I think are popular also outside of France (movies I have also been able to find with English subtitles): Amélie (one of my very favourites), Hors de Prix (Priceless), Bienvenue chez les Ch'tis (Welcome to the Sticks), Le Diner de Cons (the Dinner Game; in general, Francis Veber's movies are really good), La Haine, Ne le dis à personne (Tell No One, based on a Harlan Coben novel). And if you have an understanding of French humour, movies with Louis de Funès are classics. Two of my favourites are: La Grande Vadrouille and Les aventures de Rabbi Jacob (The Mad Adventures of 'Rabbi' Jacob).
If you have Netflix, there is a small selection of French movies on the Ireland/UK version (The African Doctor, Blind Date, Headwinds, etc. I do feel like they could add a few more interesting ones there, especially classics) and a couple of French TV series I like: Call My Agent, No Second Chance and The Returned (not for the faint-hearted; also, make sure to watch the French version since both American and French are in there).
If you have suggestions in terms of what to listen to, read or watch in French, please share in the comments for the other francophiles out there!