You could certainly increase the challenge rating a bit
I wouldn't make large moves up the dial. Maybe add an additional opponent so a 1on1 contest becomes 5on4 or such. Make slow shifts to see how your players are reacting to things.
I know I only do hard, deadly or very easy (usually random to provide setting flavor) encounters. That leads to a different resource use rate than the standard assumption. Your players will adjust.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.