To influence the path taken through an autonomous system, the Multi-Exit Discriminator (MED) attribute can be used. By setting a lower MED on R2 for routes advertised toR1 and R3, it will make the path through R2 to the 203.0.113.0/24 network more preferable.References:
Understanding BGP Path Selection, Juniper TechLibrary
BGP Attributes and Path Selection, Juniper TechLibrary

https://www.networkfuntimes.com/junos-aggregate-routes-vs-generate-routes-how-to-summarise-on-juniper-routers/

The exhibit shows that the Label Switched Path (LSP) is down. One common reason for this could be that the IGP is not providing traffic engineering information to the MPLS process. Since the exhibit shows the OSPF configuration, enabling traffic engineering extensions for OSPF would allow OSPF to distribute the labels and traffic engineering information necessary for LSP establishment.
References
Juniper Networks Technical Documentation on MPLS and OSPF