Other suggestions are better, but if they don't help the other thing I've found is sometimes it's the direction I'm moving the fabric. I tend to have that happen when I hit the corners because of how the shape/direction of my design changes to fill in that corner space.
Also, sometimes when my bobbin thread starts running too low I get that issue. So strange, but it happens. I just break thread, bury the knot, start a new bobbin, rethread & start fresh. We'd all like to be able to quilt & quilt without any thread breaks, but it's just not possible. Honestly, I'm surprised your bobbins last for 45 minutes. Mine run out of thread before then.