They need to build a cohesive team a unit without dependence on star players. This strategy can be built by a good recruitments and developments. Resources still matters, but it doesn't need to be super spending power, top players still won't come to Ligue 1 with low offered wage. Calculated strategies and consistent performances can achieve maximum points required to win Ligue 1 title.
For me the fact thst these dominance gets to be broken once in awhile has always been a sign that of others in the league aswell get to put in diligence they too can achieve such victory and not letting the league title staying too long with a particular team making the league at some point boring. The only advantage PSG has always gotten over othe teams in the Ligue 1 has been their financial strength to be able to strengthen the depth of their team but then this strength isn't shown well enough in the champions league where they are supposed to meet their equals which could actually mean that they aren't utilizing their advantage well enough such that if other Ligue 1 teams gets to wake up they are definitely going to be better contenders against PSG.
But the fear of the fact that PSG is already at the top and has got that dept and strength which most of them seem to lack has always kept them away from trying to contend meanwhile they fail to understand a limitation that comes with PSG dominance which is in the fact that they are quite dependent on their key players and that could be a problem for them of which other stronger teams in the Ligue 1 can take advantage of to getting ahead of PSG and creating that fight that could give them a chance to dominate again.