I dont like that idea. But maybe, start over with another charichter at forst lvl, but get to shose 5 or ten cards to keep. This lets you redo all the lvls and get rewards over again. Maybe keep the gold aquired also.
New thought. give the Gold and Food cards an incentive to raise their levels. maybe more gold for the cards. Extra exp for Food cards . Or collect a certian amount of gems. Just a thought. What do you think?