When I meditate I usually fall asleep…is there anyway to avoid that?

Try meditating when you are awake. I try to avoid meditating straight before bed because I am tired and distracted most of the time. My favorite time to meditate is in the mid-morning (Around 9 or 10AM) because I am fully awake by then and that helps me not to fall asleep. I hope this helps! Have a fabulous day.😁

Sleeping mostly happens when meditating while lying down, rarely when seated. Some would use uncomfortable positions but this require a high ability to meditate in any condition. Maybe you can set an alarm with a music which isn't too agressive.
Actually at first I used to sleep off while meditating lying down. And I stopped worrying about it and at some point I managed to stay up. Because mediation making us sleep means it achieves it relaxation peaks and the brain is relaxed and in good vibrations.
So my advice is what I did and do, rather than focusing on I don't want to sleep off, I'd first focus on how relaxed I feel after meditation and how rested I feel after sleeping/napping. Additionally I'll start to induce more short meditations in seated positions that are less prone to attract sleep (a seat, a room with more light, induce an lovely ringtone for a special alarm setting to avoid it to wake me up agressively).
And if I still sleep off I'd be grateful to it, as well as I'll set an intention to maximize my meditation and its effects even in my sleep / or an intention to follow through the mediation staying focused and without sleeping off in the middle or at the end/ or an intention to feel all the benefits and purpose of the mediation once done whether I slept or not…
All the best