Is there a transmission filter in 2007 prius?

nope, just drain and fill. get new crush washers before you begin, and loosen the fill bolt first

 

You need a hose and a funnel so your can poor fluid in from above, but you've probably already researched that part...

 

Some years have a magnetic drain plug, but no filter.

 

Yes it actually has a small screen filter but it is not serviceable.

This trans takes exactly 4 quarts. Take the fill plug off the side of the trans first
Before the dump bolt.

Just jack the front of the car up high as you can dump it then thread a long skinny hose funnel from the top of the engine into the fill hole.
Dump 4 quarts in bolt it backup.

 

My strategy would be to fill with the car (raised and) level, till it starts coming back out. Repair Manual info attached:

 

When I did the transaxle service on my 2006 prius, I simply pulled the car onto ramps and used a jack and jack stands to lift the back of the car to make it level. I parked downhill, so I only had to lift the back about 2 inches.

After that, it is as easy as loosening the fill bolt, then the drain bolt. Re-tighten drain bolt after draining and fill it back up. For me, the easiest way to fill it back up was with a funnel and about 3' of hose routed directly into the fill hole from the topside. I used a coat hanger to hold the funnel in place. Fill until it spills out of the fill hole and put the bolt back in. After that, lower the car and you're done. Easiest transaxle service ever. If you can change your own oil, you can do this.

Use toyota WS trans fluid or an aftermarket fluid compatible with that spec. Dont forget the new crush washers.