Learn Italian: Il restauro è molto difficile, ma lo continuo a pianificare. - The restoration is very difficult, but I continue to plan it.

This is a feature called clitic climbing. With aspectual verbs—verbs that describe the progression of an action, like continuare a (to continue to), iniziare a (to start to), or finire di (to finish)—you have a choice. You can either attach the object pronoun to the end of the infinitive, or you can "climb" it to the front of the conjugated verb. Here, lo (it, referring to the restoration) has climbed before continuo.

Is it also correct to say continuo a pianificarlo?

Yes, absolutely! Both lo continuo a pianificare and continuo a pianificarlo are completely correct and mean the exact same thing. Moving the pronoun to the front is optional, but it is very common in everyday Italian.

Why is there an a between continuo and pianificare?

The verb continuare requires the preposition a when it is followed by an infinitive verb. Because aspectual verbs take different prepositions—for example, finire requires di (to finish doing something)—it is best to memorize the verb and its preposition as a single chunk: continuare a.

Could I use progettare instead of pianificare here to mean "plan"?