Instead of looking for an "App that can do that", sit down, switch off the electronics, pick up your bass and play.
Remember all the scales you've painstakingly learned and practised, remember all the other tips & tricks you've learned, and... play.
Play for 5 minutes, play for 5 hours... just play.
Yes, it can be frustrating, but it is also rewarding. That's the whole reason why we play, the whole reason why we gather here to talk about playing bass.
The easy way is simply to PLAY.