In Ironsworn it's a bit tough to regain spirit. The best way to do it is with a sojourn. But for that you need to spend time in a community. Not always easy while on the road.
Other ways are make camp or test a bond. But they only give you +1 each.
In Starforged, they introduced this new move. It's basically the same as the heal and resupply moves (+2 on a strong hit) but for spirit.
I suggest we make use of this one too.