In my last question, I asked about a blob devouring a planet and escaping its gravity. Since simply tossing itself into the air isn't going to work, it's going to need to make itself into a rocket, and rockets need fuel.
Now, the blob itself isn't flammable, or at least no more so than most other living creatures; instead, it creates a fuel either from its own biomass, or from resources in the planet it's consuming. When it has made enough fuel, it sends a 10 foot cube of itself into space and out of the solar system, in search of new worlds. It keeps devouring and growing, making fuel, and sending chunks into space, until all available resources are depleted.
Note that it doesn't care about safety, just that as much blob is sent to other systems as possible. Given access to all the resources of a planet, an instinct and ability to shape itself into a rocket, and the ability to create rocket fuel - how would it do it?