Increase this shop's level to 100. This can be done either through spending gald or providing materials. The gald method seems relatively inefficient, so it's probably best to go with materials.
Materials are scattered throughout the world, and as you play further the level of points they provide the shop increases. In addition, when you enter the shop upgrade menu, you can see that certain shop/material type combinations have x2 or x3 multipliers. For best results, match your donations to those multipliers.
Note that if you can't reach level 100 in your first playthrough, you can use the new game plus shop to carry over your progress or have a material bonus.