Can I respec my skills and attributes?

Yes, you can respec (Note that this answer is based on to the current state of the Alpha (currently build 13 as I write this).

Once you get access to the first town, upstairs in one of the cells is a "spirit guide", who will allow you to remove previously allocated skill points (so you can reallocate them differently).

I haven't used this facility, but it says you pay for it (but I can't tell you if it's in iron bits or in experience points - I'm betting the former).

We have to differentiate between different things here, when we talk about respec.

Character Attributes

Those cannot be respecced at all.

Skills

You can remove single skills by talking to the so called "Spirit Guide" in the game which can be found in the northern corner of Devil's Crossing . After each skill point being removed, the cost for it rises significantly.

Devotion

Single Devotion points can be reset by talking to the Spirit Guide in Devil's Crossing. However, they cannot be removed if a constellation grants affinity and those have points invested.

To completely reset all your devotion points at once, you need to find a Tonic of Clarity, which can drop from Nemesis bosses in Grim Dawn.

Updated answer for the Ashes of Malmouth (11 Oct 2017) DLC:

Character Attributes
Can be respecced with a Tonic of Reshaping. You get one of this as a reward from the very first side quest in the expansion. Alternatively, you can also farm it as an epic drop from Nemesis bosses.

Devotion Points
You can reset Devotion Points with a Spirit Guide. Alternatively, you can also farm the Tonic of Clarity as an epic drop from Nemesis bosses.

Skill Points
You can reset both skill and mastery points with a Spirit Guide. The cost rises after every 20 points you reset, as follows:

+---------+-------+
| Points  | Cost  |
+---------+-------+
| 01-20   |    25 |
| 21-40   |    50 |
| 41-60   |   100 |
| 61-80   |   150 |
| 81-100  |   200 |
| 101-120 |   300 |
| 121-140 |   400 |
| 141-160 |   500 |
| 161-180 |   750 |
| 181-200 |  1000 |
| 201-220 |  1250 |
| 221-240 |  1500 |
| 241-260 |  2000 |
| 261-280 |  2500 |
| 281-300 |  3000 |
| 301-320 |  4000 |
| 321-340 |  5000 |
| 341-360 |  7500 |
| 361-380 | 10000 |
| 381+    | 15000 |
+---------+-------+