New ways to light the fire again

"Shake it up" a bit! Supplement your text with another text that approaches the topic differently. Also, make some changes in your approach to math: see how what you're learning connects to what you already know, and how each topic you encounter connects to the earlier topics. Try to anticipate what you'll soon encounter by making conjectures using what you have already covered, and/or are presently studying.

While homework may not feel like fun, you can find ways to keep math fun:

Take breaks when necessary. Try to be proactive when you study (e.g., skim through and read sections of the text prior to lectures on the same topics) and don't fall into the unpleasant trap of barely keeping up, or being "one step behind the game."

As you study, focus on the "key ideas" in the material you're reading and the problem types that are assigned. Focus on understanding the concepts and ideas as opposed to just trying to memorize formulas and just churn out answers, mechanically.

Reward yourself for even small successes.

Also, take heart. It is completely normal to "hit brick walls", for our level of passion for anything to perk up at times, and diminish at other times. Math is a HUGE field, and it is common to encounter phases and topics that just don't interest us as much as other topics have, and as other topics refuel our passion. So be patient and persistent. Chances are your enthusiasm will peak again. In the meantime, think of what you're going through as a temporary challenge to acquire the discipline to persist. If you plan to pursue math over the long hall - indeed, if you plan to succeed in life, in general - you'll need to learn how to get through the tough times and the boring times, in addition to making the most of those times in which you're aided by the fuel of passion.