Feel free to inflict 5 Obligation penalties, even if they are easy to solve.
As an example, a party on Bothawui engages in a destructive firefight with Imperial forces, and flee afterwards. Now, they are fugitives from justice in Bothan Space, and you can assign 5 Obligation for that. It is an unlikely penalty to come up, but it is a plot point to bring around if the party tries to cut through that sector again. Let it be easy to solve (maybe all they have to do is come in and answer questions), but always have it in the background.
One possibility to keep things fresh is to keep all those crime obligations separate. Maybe the party has 10 Obligation for betraying a Hutt, 5 in Bothan Space, 15 for Imperial Customs (for smuggling), and 5 for Imperial Navy (small-time pirating). Further, adjust Obligation based on how they deal with it, and maybe keep some things secret. If they bribe a customs official to eliminate their criminal records (10 obligation), maybe he was caught after the act. The party solved the customs obligation, but now maybe have a group of bounty hunts out for blood, paid for by the fired employee (5 obligation). This works especially well with larger amounts, it just has to be done so it the party can't be (unjustifiably) jilted. Returning to that example, if the party solved the customs obligation through a legal method, there will probably be no penalties; they are off the hook.