Hi Thomas Langheim,
The first step is to check if the datasource is in 3.x and 7.x
For 7.x datasource you can run RSDS_DATASOURCE_ACTIVAT_ALL program.
And for 3.x datasource, you have to run RS_TRANSTRU_ACTIVATE_ALL
program.
These are programs delivered by SAP to ease the DS activation and it will not do any cleanup.
BR
Prabhith